Next is "Saadhoonaam..." for polite supplicants he is the ultimate course. Taaraa is saying indirectly that Baali is not at all polite in treating Sugreev either as crown prince of Kishkindhaa or as his own younger brother. As such Baali cannot supplicate to Raam at this stage for his impoliteness to Sugreev and to Roomaa, wife of Sugreev, which is intolerable to Raam, and hence Baali should not confront Raam. "Aartaanaam..." used for anguished supplicants in earnest Raam is the ultimate recourse. Baali may dismiss this idea saying that "if Raam is the ultimate course for the polite supplicants, I have my recourse to other supreme lords, i.e., none other than Lord Indra...'" And for this Taaraa is supplementing her thought in saying, "yashasah cha ek bhaajanam..." by grace Raam is the only ultimate abode, where Indra and others are but penultimate. Hence as long as Raam is standing to guard Sugreev, Sugreev cannot be trivialized.

Alternately, it is again as said later in Geetaa, 7:16 that 'chaturvidhaa bhajante maam... four kinds of devotees worship me...' Those four are:
(1) One, who is seeking knowledge [Saadhoonaam, those that are interested in salvation, Kaivalya Kaamuk, like Raajaa Pareekshit.]
(2) Two, seeking of material gains [Aapannaanaam, those that seek the material gains that were not there previously to them, also called Arthaardhee, like Sugreev, Dhruv] 
(3) Three, who is distraught [Aartaanaam, those that are in anguish like Gajendra, the Elephant caught in water by crocodile in Gajendra Moksh]; and 
(4) Four, the one who is a wise person, Yashasah, Gyaanee, gloriously enlightened one, like Shuk Dev Jee, Sanakaadi Muni, Naarad Jee, Pitaamaha Bheeshm, Prahlaad etc] And this wise one is impossible to exist and if he is there "he is my soul...gyaanee tu aatmaiva me matam..." Geetaa, 7:18. For all these four kinds of people Raam is ...ek bhaajanam..., the only recourse.

Next is Gyaan, Vigyaan, Sampatti. Gyaan is a privy to the materialistic, worldly, kingly affairs. Vigyaan is the knowledge derived from the scriptures, providentially profound, or through "karmaadhaaraya, gyaanah cha asau vigyaanaa sampannah cha..." corporeally he is the knowledge, and spiritually he is Gnostic as well. Hence he is the phenomenon of the Supreme Being in maintaining Dharm.

In order to maintain that Dharm, Raam is now observant of his father's orders "...nideshe niratah pituh". This pursuit of father's orders is but one of the many other attributes of his Dharm, and that alone is said here as secondary attribute, "upa lakshan". Hence in pursuing his Dharm Raam may eradicate A-Dharm of Baali, insofar as Baali's misdemeanors towards Sugreev and his wife Roomaa. "Gunaanaam Aakaarah", with his auspicious merits he is a Great Mine. Usually these Gun of Vishnu are six, as per Vaishnavites' classification, stating them as "Shadgun Sampatti", which are Aishvarya, Veerya, Yashas, Shree, Gyaan, and Vairaagya. And there are many more in the depth of the soul of Raam hitherto unexcavated. So are the innumerable auspicious elements, "Dhaatunaam Shailendro...", the elements that neither subdivide nor shake him off his Himaalayan personality, in the pursuit to establish Dharm.

Why Raam Killed Baali from Hiding?
[ Valmiki Ramayan, 4/17]

Baali's killing is a puzzle from the viewpoint of Imperial politics and Dharm. Hence Baali questions Raam logically about it even at his dying stage. The questions are as below:

(1) By killing one who is facing away, what worth is achieved by you?; (2) You have not punished the wrongdoer; (3) Killed one who is combating with another and an unvigilant one; (4) In your country or city I did no misdeed; (5) Non-guilty being is hurt; (6) Fruits, tuber eating being is killed; (7) No dispute of land, gold or silver; (8) Your primary aspiration is to kill without probing into good or bad; (9) How will you face criticism by scholars?; (10) Unnecessary killers are hell-goers; (11) Un-wearable is my skin uneatable is my flesh; (12) Five kinds of five-nailed animals are usable by humans; (13) I would have brought back Maithilee in one day.

For all these questions Raam answers in next chapter and speaks as to how justified was his elimination, to Baali and to all of us.

[ Valmiki Ramayan, 4/18]
Explanation to Baali's question (13) "I would have brought back Maithilee in one day..." is interesting to read, that is why it is given here. Any truce between Baali and Raam is an impossible and improbable proposition. Why, because what Raam wanted was only the "search for Seetaa..." not to bring her to his fore. Elimination of Raavan had to be done by Raam only, for which Seetaa had to be located first. If a truce got struck between Baali and Raam, Baali straightway went to Raavan and asked for Seetaa. Raavan for sure refused to yield her. Then a combat must have ensued between Raavan and Baali. But Baali could not combat one-to-one in a duel and he could not encounter the magical war of Indrajeet or Kumbhkarn. Then all the Raakshas would have eliminated Baali. And thus the epic had concluded haphazardly.

Other way round if Baali sought the help of Raavan and his military, all would come down on a handful warriors like Raam, Seetaa, Sugreev and Hanumaan etc, and the whole of monkeys force will be with Baali, and these few warriors will be uprooted down mercilessly. Above all, Raam had already promised Sugreev to eliminate Baali, the abuser of tradition, and faulting of Raam on the word accorded is blameful. Hence the simplest formula 'friend's enemy is my enemy too...' worked well and Raam followed that only.

[ Valmiki Ramayan, 4/18/43]
There is none to say that Baali is 'unkillable...' or 'not to be killed...' But to everyone a doubt occurs as to why Raam did not come face to face with and killed him? Why did He shoot him from hiding? For these doubts, the above said arguments may not suffice or satisfactory, either to Baali or to us, the readers. The only commentary on Raamaayan insofar as Dharm is concerned explains that for us.