Their methods are not a motte and bailey, but rather a fundamental demonstration about how they've been put above straightforward Constitutional law. When I see the thugs who murdered Renee Good and Alex Pretti behind bars, then I will start entertaining the idea any of this is about immigration enforcement.
I'm not questioning the validity of what they're claiming to police, I'm questioning why the overt capital criminality we do know about has gone unprosecuted and unpunished. If a city only had one murder in a whole year, and they knew who the perp was but refused to arrest and prosecute, would you call that sensible policy?