The logic you presented goes against rational business sense, meaning that you are assuming that the decision takers dont act rationally, meaning that they are idiots. You think that such an assumtion is a good one?
If you want to make an argument against MS buying this DLC based on that MGS DLC exclusive might not be attractive, feel free to do so. (il probably even agree with you) So far you have tried to create arguments that are not based on this at all, rather you have tried presenting arguments as to why Konami should reject such exclusive DLC deals etc, arguments that go against even the most basic business logic.