I don't know if this should be considered as a serious death threat, it seems more like shit talking because of dislike towards the other person. So don't take it too seriously, unless he goes on ahead and tells you "I am gonna kill you" or something that actually implies a serious death threat. This given very little context, feels more like a person being butthurt and saying : "why u posting in my thread, oh no guy with trust rating gonna give me neg trust, i am gonna swear goats at u fuck u fuck ur mom fuck dick u big gay".

And if you don't like interacting with this user, ignore and move on. Some trolls aren't worth the sweat.