Trump decided that!He tried playing nice. It didn't work...He changed his mind.
If that's the case, then he has the most classless, bush league, unprofessional way possible of making that known. In reality, if he wanted the DOJ to reopen an investigation of the Clintons, or anything else, that should have been done in private for many reasons, including that it is not smart to announce an investigation is underway as long as it can be kept quiet.