They don't need solid excuses, don't need to find any errors, they'll simply denaturalize him, say something transparently flimsy, call it a day.

I think the real story is how afraid they are of this man. Conservatives don't give a flying fuck about NYC. It's often pointed to as a liberal hellscape. What they're afraid of is Mamdani's policies and actions showing real progress for the city. If they really thought he'd be a disaster, they'd let him tear the city down.