Tell your friend that this course of action failed, as us in the present are still experiencing issues.
Well, that's _this_ timeline. Other timelines never had an outage.
Not with Terminator rules…
I couldn't comment on the causal hazards but since time is currently having an outage they've got an improved shot at getting away with it. I say go for it.
Very unproblematic. Your travelling back will land you in a freshly branched universe with no way back to the one you came from, so no worries there.