I'm not actually convinced it was Vance specifically. Their support seemed to grow a bit after the US election gave their movement a bit more legitimacy, but then started back the other way when people saw what it means in action. Vance's visit was timed at roughly the peak, but, snark aside, it's probably more correlation than causation.
The actions of the Trump administration as a whole are a more plausible cause of any slight erosion of support.
Yes, please.
Signed, the other NFC West teams.