Why is Momoshiki being assumed to function like a Jin and will break Boruto out?
Are you asking why Momoshiki is going to protect his vessel from getting his mind destroyed, incacipated & the possibility of death post the genjutsu?
I cannot remember a single Genjutsu resistance feat in Boruto.
It quite literally does not matter nor is this a non defeater. Boruto
atp in this story is already 80% Otsuktsuki, meaning he has Ostukstuki DNA which is
accepted to resist genjutsu on their own right. If there's a contradiction and that isn't enough, again, this argument is foolish. We know Momoshiki emerges whenever is vessel is out of Chakra or has lost consciousness, and with how potent Itachi's Genjutsu is? He's going to break Boruto's mind similar or even greater than Kakashi was and he's going to pass out from the sheer pain and stress the Genjutsu causes on his mind, which is when Momoshiki will emerge and rock his shit to hell. The argument doesnt help if he uses something like Tsukuyomi, If Highly Trained Kakashi managed to stay conscious after Tsukuyomi, how do you think Boruto, a kid, will react to High Potent Genjutsu? He's passing out in like 2 minutes.
Like i said earlier, Momoshiki functioning as a Jin simply doesn't work
Aside from cooperation, another reason why having a partner nulls genjutsu is because the partner (a tailed beast in this instance) has its own chakra which can be used to disrupt the host's own chakra
Momoshiki doesn't have his own chakra here. He's entirely reliant on the chakra from boruto to function. The chakra that's already under the influence of genjutsu
And with the scan someone sent above, having a partner still doesn't help when it comes to tsukiyomi (or a high enough genjutsu
This argument makes 0 sense. Addressed most of this above.
No one is equalizing Jinchuruki's to Ottsuktsuki like you guys are rn. Momoshiki is a soul or spirit. He does not clinge to the physical world and does not exist in a physical sense just as any Jinchuruki, nor does he rely on any Chakra to function, he is already physically dead. His "Biological" Otsuktsuki data is encrypted into Boruto and he simply possesses him (as ghosts do) whenever a chance arises, giving him Otsuktsuki powers and capabilities. Such as here, when Boruto passes the absolute hell out from Itachi's hellish Genjutsu. Itachi is going to die. And this makes him incomparable to any Jinc, Momoshiki does not have as much free will with possessing his vessel just as they can, only under certain limited conditions, which are met here.