I don't think they want the vaccine to kill people, or at least not a lot of people, just deadly enough that smart people won't want to take it but dumb people will just do it. The people most likely to take are the people that are easiest to control and will give them their vote in almost any circumstances, so it doesn't make sense for them to want to kill their own voters.

I think a more likely reason is they want to identify and weed out the uncompliant, especially from important government jobs like police and military. Then they can use their new stormtroopers to enforce unconstitutional edicts on anyone who opposes their rule. If you think the lockdowns were bad when police officers were just afraid of losing their job, it's only going to get worse as the percentage of police officers that enjoy making people suffer increases.

States need to stand up and start passing laws against this kind of thing. Even if they already have them they need to do it again if for nothing else than on principle to help re-enforce the idea and help embolden other states to do that same.