It's a good story. It does succeed in making Root interested in what the real story is, though it's entirely aside from the point. Maybe later she'll get a chance to pry the truth out of Peter in a better setting. She'll buy him boba and everything.

"No one's called me a shrew while I was torturing them before," she muses, "so you get points for originality."

Root stops at the other side of the slab and clicks her tongue at his now-clenched hand. "I'm going to move on to your feet if you don't cooperate. Come on now. Time for the other thumb!"

It's messier to get a foot broken enough to fit through an ankle restraint, but if Peter is determined to be difficult, she can get to work on that. It's a purely practical standpoint; Root isn't enjoying hurting him, it's just something she's good at and knows will get the job done. If there was a better option, she'd stop in an instant, at least to make the Machine less disappointed in her. But in the meantime it's full steam ahead compartmentalization, which has always been her specialty.