Considering that the original plan was for Sisko to be in Lily’s place, its safe to say he would have opposed Picard’s plan. There's history between Picard and Sisko, and it would be a huge oversight to not callback to that if Sisko was in the film.
And even if both Sisko and Lily are in the film, then they both oppose Picard’s plan. Which would just highlight Picard going off the deep end even more, with calls for a more sane approach coming from someone from the mid-21st century and one of Picard's peers from the 24th century.
And even with O'Brien, he could have been in the place of Daniels (the Ent-E guy, not the dude from ENT) for the film.
O'Brien I can see, though I would have been disappointed if he didn't say something about Picard becoming a whackadoo.
Sisko though. I think Sisko would have resolved the problem Q-style. And I might have been cheering for him to do so.