FBI is flooded with more dangerous messages than what the guy wrote content wise, messages written by trump supporters to many Americans of all walks of life, messages that have home addresses, phone numbers, paycheck information and location of their work posted publicly and with encouragement to go do a number on these victims. These messages are more intimate, yet the FBI response was, we will just wait when these lunatics act on their threat.
There is a backlog at FBI. some DUDE WHO DOESN'T LIKe GAY PEOPLE won't probably hit their top list. And I bet most FBI officials might be laughing at the messages, America in general hates homosexuality and homosexuals. Best option is to reason with the guy and educate him how threats don't accomplish anything.