And what is he advising Duryodhan even now?...
"...Hearing these words of his, the Kuru king Duryodhana became of cheerless heart. Eyeing him, Santanu's son said,--Listen, O king! Abandon thy wrath! Thou hast seen, O Duryodhana how the intelligent Partha created that jet of cool and nectar-scented water! There is none else in this world capable of achieving such feat. The weapons appertaining to Agni, Varuna, Soma, Vayu, and Vishnu, as also those appertaining to Indra, Pasupati, and Paramesthi, and those of Prajapati, Dhatri, Tashtri, Savitri, and Vivaswat, all these are known to Dhananjaya alone in this world of men! Krishna, the son of Devaki, also knoweth them. But there is none else here that knoweth them. This son of Pandu, O sire, is incapable of being defeated in battle by even the gods and the Asuras together. The feats of this high-souled one are superhuman. With that truthful hero, that ornament of battle, that warrior accomplished in fight, let peace, O king, be soon made! As long as the mighty-armed Krishna is not possessed by wrath, O chief of the Kurus, it is fit, O sire, that peace should be made with the heroic Parthas! As long as this remnant of thy brothers is not slain, let peace, O monarch, be made! As long as Yudhishthira with eyes burning in wrath doth not consume thy troops in battle, let peace, O sire, be made! As long as Nakula, and Sahadeva, and Bhimasena, the sons of Pandu, do not, O monarch, exterminate thy army, it seems to me that friendly relations should be restored between thee and the heroic Pandavas! Let this battle end with my death, O sire! Make peace with the Pandavas, Let these words that are uttered to thee by me be acceptable to thee, O sinless one! Even this is what I regard to be beneficial both for thyself and the race (itself of Kuru)! Abandoning thy wrath, let peace be made with Parthas. What Phalguni hath already done is sufficient...
...Sanjaya continued--'Having heard these beneficial and peaceful words fraught with both virtue and profit, thy son, however, accepted them not, like a dying man refusing medicine."
Last two passages, though not directly related to Shikandi's role, they amply underline the role of Arjun- As per Vyas. And that's what I have been trying to say- that's how i'd see 'Author's intent'. Permit.