Nitpicking a stupid non canon fanservice scene in and of itself is stupid. But let's engage in the Yonko fan madness.
no it's clearly stated by leakers that it is only against shanks (don't include his crew).
The leakers stated that the Marines didn't want a war.
And that Shanks & his entire crew were present at the place to fight against Uta's monster or whatever. You think Shanks's crew won't help him at all lmao? You think the Marines who saw that and know that (the Gorosei even asked Shanks to go there in the first place) won't factor that in? lol.
Shanks is different from other yonko(kaido and bigmom are both born with monster strength and defence ). Shanks is not like that. So he has to rely on haki to make kaido admit that shanks put alongside roger and WB.
Doesn't change the fact that they have just as good CoC as Shanks. Luffy & Kaido recreated what Roger & WB did.
At best, Shanks' CoC is slightly stronger that's all.
As for why tama and others didn't get knocked out with bm haki. it is because bm haki not targeted at them.
BM's haki wasn't aimed at random gifters who were K/O'd there as well but yet they were getting K/O'd lol. Usopp, Nami, Tama & Speed weren't. No excuses around this.
Plus what proof do you have that Shanks would randomnly target Momonga alone specifically and K/O him when leaks say he used his Haoshoku to threaten the Marines in general lol?
Just accept that it's a fanservice scene in a non-canon film and move on. Heck, Strong World also had Oda working in it, but I doubt you'd agree that Roger's Rival Shiki would lose to Pre-TS Luffy lol.