Well Flake is known to be pretty um, flaky himself.
He is part of a gaggle that doesn't understand that unless he's removed or resigns, Trump is here for four years. This isn't a liberal college campus where you can attack like a bunch of bees with cute words cobbled together in clever arrangements to make opponents cower and fear and run away. Continuing to throw ones self againts the mountain while screaming out Trump's character shortcomings isn't going to change anything, just result in futile self-damage. It's very doubtful the mountain is going to move.
Particularly for public officials like Flake, they need to suck up, buck up, and try and work with the guy to get things done. It isn't the Executive branch that has failed to pass meaningful legislation in 6 months, so maybe the senator should shut the flap yap and get to work.