I disagree.

It’s reasonable for Flake and other Members of Congress to vote for legislation they support. But it’s important to distinguish normal (albeit contentious) political disagreements with problems unique to the Trump presidency. I’m happy to support anyone who shares my concerns about Trump, whether or not we agree about anything else.

I made this argument in greater detail here:

Hey 'Resisters,' Is Trump an Existential Threat to America Or Not?

Also, he hasn’t voted with Trump 100% of the time. For example, he voted for the Russia sanctions bill, which Trump strongly opposed (but Congressional support was veto proof and the president signed it rather than get embarrassed by an override).