Creating FOSS does not get you in trouble with the law. Creating things that are against the law gets you in trouble with the law - FOSS or otherwise (in Zimmerman's case, even if PGP were proprietary, publishing it internationally was illegal). I have a hard time seeing why a FOSS project* would care about discord ratting them out in case of illegal activity if they weren't doing any. Unless the idea of FOSS is illegal, as your comment suggested, but that is plain false (in your example and in all jurisdictions I am even remotely familiar with).

* - except for things like Signal, Tor..., which are illegal some places, but they probably wouldn't even consider Discord in the first place