At the start of that scene, they’re inflicting harm that would still allow the dude to do everything he’s done so far, just scarred. And the scars are appearing on his future self. It makes a kind of weird sense, if we stretch our imagination.

But they cross well past anything reasonable into injuries that would have just made anyone’s past self decide to retire and hide out in the woods in Florida.

It made no sense at all by the end, that his future self was somehow still working for them.