Are you there? Because I don't think you can say he headbutted him the second time. To me, it looks like he's diving on top to cover for two because the kid bellied down after the first impact. Maybe you're there and saw it live though?
Regardless, the real reason he got DQ'd was because he showed up the bald judge at the bottom. The ref on the mat initially gave nothing (grounded). Then the bald judge was pointing at KV, so he gave caution + 1 to KV (fleeing) thinking that's what the judge wanted. Then the judge calls them over and gives KV an attention and chides him. KV kind of smiles and shrugs his shoulders and walks back to the center with the ref. At this point, the judge sees that, gets mad, and immediately calls the ref back over, changes his mind, and argues for the DQ.
Was first headbutt ill-advised? Maybe, but there's a pretty legitimate attempt to score there on the edge. That's a sequence we see all the time in freestyle. But the bottom line is the bald judge got his feelings hurt, and took it into his own hands.