(this ended up being way longer than I thought it would, so tldr: I’m not saying that sam is evil or that he’s victimizing bob, I’m saying that it would make a lot of sense for sam to be uncomfortable leaving bob with the new avengers and he would be totally justified in feeling that way.)
okay, lemme make my stance clear, which is that in this hypothetical scenario, I don’t think sam is wrong.
the thing that’s so compelling about civil war is that both steve and tony make reasonable points. on a political level, the avengers do in fact need some sort of supervision, but also ross is awful and team cap just got done rooting out hydra from the american government. on a personal level, it’s shitty of steve to hide the “bucky killed your parents” thing from tony, but tony’s reaction does also sorta prove why steve did it. neither steve nor tony is fully right or fully wrong in civil war.
I’m not proposing a scenario where bob is a sad victim and bucky is his noble defender and sam is the evil, unsympathetic villain out to get them. I’m saying that it would be in-character for sam to have doubts about the whole setup—and he would be well within his rights to.
sam has a strong sense of justice. he doesn’t blame bucky for things he did under brainwashing. he understands the flag smashers even if he doesn’t agree with their methods.
but he’s also pragmatic. in the winter soldier, he knows bucky is brainwashed, but he still tells steve that maybe they need to stop bucky and not save bucky.
why? because bucky is dangerous. he’s a brainwashed assassin with an insanely high kill count. he almost kills sam and he almost kills steve. and at this point in time, they have no idea whether or not the brainwashing can even be reversed. and sam is right! the movie literally shows steve almost dying because he’s unwilling to hurt bucky. yeah, bucky ends up saving steve in the end, but steve wouldn’t even be in a position of needing to be saved if he had been willing to take killshots against bucky.
(which is not to say I think steve should have killed bucky—but sam’s take on the situation is very reasonable, and objectively makes more sense for anyone who’s not emotionally invested in bucky the way steve is.)
back to hypothetical post-thunderbolts scenario. bob is like. objectively dangerous. he’s the equivalent of a walking nuclear bomb. it’s not his fault, but… he can’t control his powers. manic episode? oops, sentry comes out. depressive episode? oops, the void comes out. literally the only thing stopping him from killing everyone in manhattan was the power of friendship.
and yeah, I’m sure bucky would tell sam that the power of friendship can stop the void! but sam did not watch thunderbolts. sam does not have the same trust in yelena or john or ava or alexei that the viewers have. what sam actually knows is that valentina allegra de fontaine (a woman with incredibly shady morals who triggered the void once already) is in charge of a team that contains:
an ex-black widow who got de-brainwashed and then still kept taking on contract kills and worked for valentina voluntarily
john walker. which. falcon and the winter soldier. and then post-fatws he became a mercenary. and john also worked for valentina voluntarily.
an ex-shield operative who tried to kill ant-man and then went around doing contract kills and working for valentina voluntarily.
an alcoholic, ex-soviet superhero who spent twenty years in prison and did not work for valentina voluntarily but only because she wouldn’t hire him.
like. you have a guy who could destroy the world if he has a bad mental health day. this is not the team lineup any reasonable outsider would trust to keep him mentally stable. and they’re working for valentina, who, again, caused this whole mess in the first place and tried to use bob’s powers for her own gain.
we as the viewers can say “oh but the new avengers are a great team and bob’s friends” because we have the advantage of having seen the movie. which is literally designed to make you think of them as a team and see how well they work together. sam does not have that benefit. sam is looking at a team of the most mentally unstable, unethical, antiheroic misfits earth has ever assembled. and bob.
I’m not saying that in this hypothetical, sam wants to lock up bob and throw away the key, or kill bob, or even hurt bob in any way, really. I am saying that it makes a lot of sense for sam to want to remove bob from the thunderbolts and valentina’s influence. and honestly? he’s totally justified. this whole setup looks like a powder keg about to explode from the outside, except instead of a powder keg it’s a nuclear bomb.