Him being registered republican doesn’t necessarily mean he still feels that way. He made a blue political donation. Some people register with a certain party just because their parents are present when they sign up.
I don't think there is currently enough public information to build an accurate profile on him.
You can look up the receipt on the FEC and the address is listed as 2506 Milford Drive, which is the same address as his voter registration and what's being reported on the news. I keep seeing this "there is another Thomas Crooks" narrative online and wanted to confirm myself.