Answer: no - gentle heat does not bother cured epoxy. So I was lightly grinding on the part and the adhesive was fine.
Cutting off the alignment dowell and the end glowed red hot, then the epoxy burned and dripped/fell, but the part on the other side with more mass was fine.

aside.... this mis-naming really annoys me for some reason.
> Cure time for 5-Minute Epoxy is 45 minutes to 1 hour for a functional cure. Full bond strength is reached in 16 hours @ 24°C.