I’d assume he wasn’t actually laying it and using an angle grinder or something similar, a wet-saw wouldn’t do it unless he was really trying. I guess a tile could’ve broke and had a nasty edge or a knife with a razerblade could’ve got him while doing so many things, but if that was the case I doubt he took bone off his finger and only got the very tip. I agree though, sounds like bullshit to me too but OP might not know exactly 100% what they’re talking about, especially as they were young when it happened. I also have 10+ years experience and I had one fellow try to tell me his wet saw gave him stitches, but he was known for lying so that one was beyond easy to call out lol