Marco gives up when in front of King and Queen at the same time and he's already exhausted enough for Perospero to notice it from the distance while still having a 2 versus 1. If anything, the only valid conclusion you can extract from this is that King had it easy and still wasn't capable of winning by himself.
It's not like this matters, anyways. The clear message is that Marco exhausted his abilities and had trouble to keep fighting because, as he commented, it's hard to face two billion combatants at the same time.