It's because their interest is the same as the Prime Minister's. They don't want to see the Prime Minister, whom they serve, run afoul of conflict of interest. That would cause both political and legal problems. They are there to make sure that he complies with the law. It is their duty. They have been assigned that duty. Surely they're going to exercise it in such a way that there does not appear to be or that there does not arise a conflict of interest. That's their job.
