Another reason Silver wasn't in TMOSTH is because he could probably just suck the poison out of Sonic with his powers.

I always like wondering to what extent Silver's powers can pull things off; in IDW, when Super, he could inflict changes on a molecular level, and I think it would definitely be interesting if he could do so in canon as well! It would make him even more OP for sure, but it would also give him something unique. And besides, I figure it would be a huge struggle for him to do something so tiny and precise, so it'd be nice to see him actually struggling with his powers for a change! After all, usually we only see him struggling when he's overly straining himself and trying to do too much at a time, so contrasting it with something absolutely miniscule that also gives him issues would make for an interesting scenario imo.

Though, I doubt he'd actually have been very useful in un-poisoning Sonic: after all, everyone thought Sonic was simply playing along and napping, and by the time Silver's powers would have been useful Sonic had already come around again😅 Still, his efforts would be appreciated!