Actually I figured Roy was doing it intentionally even without knowing about the dungeoncrashing rules because of his facial expression. The flat or angry eyebrows as he's taunting and taking the hits from Thog just made me think it was on purpose, something which made a great deal of sense shortly afterwards.

Man, really the entire unarmed fight with Thog is just one big example why Roy is my favorite OotS character by a longshot.