I find thats unsportsmanship as they dont play the game as it was intended. And its a unskilled way to play. In a game like Halo where there are a lot of momentum changes due to Power weapons and map control switching, gaining a "little" lead of like 10 kills can easily be overcome with the momentum change of regaining power weapons and map control. Basically, they just need to get the power weapons first, use em to get there lead and hide like a ***** for the rest of the game. Dont get me wrong, hiding in the last 1 or 2 minutes is legit, but not when you glitch out the map and use unintended knowledge of ways to cheat the game to win.
Its like saying its skill and fair if I know how to mod the game and use it online. Or atleast that superjumping in Halo 2 was fair... Something Bungie was very clear when they said it was cheating.