It depends on the outcome of the strike. If Fain leads the union to major gains for members and then says Trump is bad for the union that holds a lot of weight and could be enough to sway the couple thousand voters in swing states away from Trump. Remember 2020 was decided by around 40k votes in 5 states.
Exactly, one way to change people’s minds is to give them the results they need while being clear about where it comes from. You won’t out promise trump, he got Ohio by swearing up and down he was sympathetic to our steel and coal workers. He swore miracles. Fain is helping our auto workers take what they deserve, what they need. When the food on your table and the roof above your head are there thanks to the union and they make sure you understand that then you aren’t looking for some gold covered businessman from the coast to convince you he understands and will hurt the right people for you and in doing so work miracles.
I think a lot of folks have already written off a lot of places that are traditionally won or lost politically on union power. Strong union gains might even bring cracks in how heavily stacked some former swing states are.