It all depends what deal he's signed with Wilson. Don't forget Ott would likely not be in the WRC right now if not for Malcolm. Look how many chances he gave him and how much work he's put into Ott's career. He's also a shrewd businessman so it wouldn't surprise me at all if it's written into Ott's past contracts that MW will take a cut of future earnings.
You get the same thing in football all the time with sell-on clauses. I have no idea whether this is true but I mentioned it on the forum about Ott a couple of weeks ago.