This is just crap, if they have profitable mining rigs then why don't they run them for themselves and collect the coins instead of renting them out. Something smells. Nobody in their right mind would rent our mining power for less than what it makes.
There is the same recurring argument about mining hardware vendors: why do they sell hardware instead of keeping it for themselves?
Easy:
- First of all they ARE taking a cut on the mining profit (covering their hosting running costs + a markup)
- By selling mining capabilities they are less exposed to the bitcoin rate variations, this risk is offloaded to the miners
- They get the money now instead of later