In his murderous rage Marcus became completely oblivious to the realities of the world.
He did not care what Max's power level was, he did not care what Max's position in the military was, he did not care if he was going to get hurt in the fight against Max, as the only thing that mattered to Marcus in the moment was to hurt Max, as only by hurting Max could the pain in his mind be numbed.
It was a stupid decision, one driven by nothing but a broken male ego that could not see the woman he obsessed over being claimed by someone else, and hence, breaking military rules, Marcus marched straight towards Max's office and unleashed a sword attack that sliced the whole structure in half.