Haven't read the whole thread, so I'm not sure how much info is out. But this was booked as a work, they called Mark at the last minute, and obviously, he needs the money. Because he hasn't been doing any real training, it was supposed to be a real short match, with Mark being told be was winning with his early UFC's neck crank.
But, they totally double crossed him. Knowing that he would gas out quickly, and not really be able to do anything about it, they wanted to use his name over there, to get this douchebag over by beating him. So, the Sumo guy didn't technically just go into business for himself, he followed the orders he was given. It's not like they told him to lose, and he went out and did this. He did what they wanted him to do, to go along with the script until Coleman started to gas, and then to take advantage of him.
And as you can see by the fact that he tried to finish him, and couldn't, despite Mark barely being able to stand, and STILL being taken down by Coleman's Zombie takedown/collapse, he is useless.
This is just another one of Inoki's typical idiotic plans, that he thought was going to draw huge attention, and turn this guy into a major star, and turn the industry around over there again.