You don't provide a link,so I can't check your source. But the whole issue of who appointed Reinhart arose after DMB linked to a Rassmussen Reports tweet that indicated that they thought it was fishy that Reinhart recused himself from a civil case where Trump sued Hillary, and yet was willing to sign off on the warrant for the search as a criminal complaint...
When I searched I saw multiple accounts that Trump had hired Reinhardt and that's why he recused himself. Now it appears that he was actually appointed by judges, so the whole claim that he would have even been in a position to preside over the Trump lawsuit, much less need to recuse himself seems like a fabrication...He donated to both Obama and Jeb Bush's presidential campaigns and his wife was appointed by then Gov, now Senator Rick Scott...
His boss describes him as "meticulous", and at one point he worked in the ethics Department of the DOJ. I think it was just the luck of the draw that he was assigned the warrant sign off duties on Fri when the DOJ sought the warrant for the Mon raid. They obviously wanted to minimize the amount of days prior to the raid in order to maintain secrecy. And since he's requested for the DOJ to unseal the warrant by Aug 15, I'd say he found the evidence presented to him compelling enough to move forward with the raid.