we know nothing about what the goblins are like, in theory someone could keep their alignment when they turn into a goblin, or different goblins could have predetermined alignments (possibly including town). We can make a strong guess that the green goblin is probably going to be anti-town though, so thats one baddie and five unknowns.
I would say freddeh is incentivized to try to become the green goblin and that we should do what we can to stop that from happening. Not entirely sure what that is though.
Lynching the slot seems like a waste. Fred will just pay bail and we don't get anything out of the character name reveal. He has three layers of protection, can roleblock anyone who targets him, can prevent himself from being targeted, and has an extra life. He's also immune to being roleblocked. For all intents and purposes it seems like he's unkillable and undisruptable, so we can't really mess with him through actions either.
If anything can stop him/slow him down at this stage it would be characters with "silver bullets" that happen to bypass most or all of his defenses. I think there was a role in the last game where if they hammered someone that player was killed instead of jailed? I'm not sure if protected would stop that, but something similar could probably work. Its also implied via his abilities that he has a couple specific achilles heels in the form of mendel strom and harry osborn, so whoever can exploit those could choose to do so.
I'm still not convinced "dealing" with him is the right thing to do though. His role seems like a huge asset to town as long as he doesn't go goblin mode.
His items are public knowledge, and so one thing we could do is have him sell the lab equipment and not get a new one, and then check on him once or twice a phase to see if he's gone against that. The wording of the ability makes it a bit unclear over whether he'll automatically generate a new lab equipment whenever he doesn't have one or whether he needs to choose to get another one as a free action though.