As far as I can tell, the evidence for the hole being drilled then epoxied on Earth amounts to nobody wanting to believe the alternative (that it was drilled while in orbit.)
The epoxy was applied on the outside and was later covered by insulation. Here is a picture from the EVA where they cut away the insulation and located it: https://i.insider.com/5c112efc4a8213310205a17b
I’ve worked with epoxy quite a bit, and delaminating is one of its failure modes. That is, sometimes it flakes off cleanly without leaving much behind.
Having said that, it’s hard to believe that there wouldn’t be traces of epoxy inside that very rough hole, or in the bare metal exposed by the drill bit. So it seems odd to me also.
Here is the hole. Personally, I don't see any trace of epoxy in or around this hole: https://upload.wikimedia.org/wikipedia/commons/3/3f/Hole_in_...
(To be clear, it's the small hole, not the big one next to it. The small hole next to the paint marred by a slipping drill bit.)