As usual, we do not know what the actual facts are.

If I were the guy, I would put the word out, loud and clear, that I was leaving a Tx on, on channel xx, all the time. I would then do as I normally do and not leave a Tx on unless I was flying. The threat may be achieving his desired results.

On the other hand, he may not know what he is doing is illegal and may be a law abiding type that would quit when he realizes it is illegal.

Or... he may be a jerk

In any case, it is unlikely anyone is going to call the FCC and complain... whether he is a friend... or an enemy.

I guess, if anyone really wanted the FCC to go after him, they could say they thought he was a terriorist planning to use an RC plane for evil purposes.