Lump having an INT of 19 without the headband does make a bit of a nonsense of his story. I'd not noticed that.
Surely it wouldn't nerf him significantly at the levels we're talking about to make it 17 instead? Personally, I don't care if it's a bit of a cheat and he has 17 anyway, or what his stats are when dead, as long as there's no functional difference between how he's built behind the scenes and him being built with lower intelligence and using the headband.