Because in Bunnell's book he wrote, that Chief Tenaya spoke a "Paiute Jargon".
Which meant that Ahwahneechee was a dialect of Paiute.
Even Jay Johnson who is leading the effort for federal recognition acknowledged that the dialect spoken at Yosemite was a similar to Mono Lake. That would indicate that Ahwahneechee was a dialect of Paiute and not a dialect of Miwok.
Every instance in the book goes back to Mono Paiute or Monache Kaweah, or Norther Paiute and all of those three Paiute dialects combined.
NOT ONCE does the book say he speaks Miwok or that he is Miwok.
That is why on the Petition to Cogress on Behalf of the Indians, it says "Yosemites, Monos and PAIUTES" not Miwoks, Mewoos, Mewuks any Poyotanees, Nutchus or others.
Because they had their own rancheria that was disolved at Merced Falls. The rest had the Big Creek Rancheria in the lower Tuolumne. The Paiutes had the upper Tuolumne, that is also documented.
What makes you think that Poyotanee or Awalances were EVEN MIWOKS? They certainly weren't Ahwahneechees.