Who would be worse to get your butt chewed out by: Mattis or Trump???
I’m going to say Mattis, but not because Trump doesn’t have it in him. It all depends on the venue.
Seriously tho, if it was an honest human mistake, I think both would be fair in the end, and not take the opportunity for pointless humiliation for its own sake.
I believe they're both teachers by nature, and would feel somehow unsuccessful in the encounter if a lesson wasn't imparted.
On the other hand, if it was a mistake from utter carelessness, yikes to either ! ;-)