Did Maxwell make them sentient, actually? Because if not, he kind of just threw three metal mannequins at Silver...
I'll try to avoid that in the future, but tbh none of the enemies aside from Maxwell are really able to give Silver much of a threat yet. You'd need something big and independent, and I don't think we really have room for something like that in the True Lab.
My current thinking is that, with Blaze's current position, Maxwell might be able to put her under threat while Frisk is distracted with... something, causing Silver to make a reckless psychic outburst. I'm going to reference this more later in the RP, but everything Silver's been through plus his powers means that he isn't exactly the most stable 14-year-old in terms of mentality. I mean c'mon, the dude raised himself in a post-apocalyptic world as an orphan with only Blaze as his companion, fought a mad doctor, an entire government and a fire demon, and STILL hasn't been able to fix his time.