Got a scary letter from BIL in GSYC(NJ)

Hi all Hopefully I tagged this correctly. I don’t know if it needs to be worried, advice, or questions or what I just need help I guess? Has anyone been to “yardville” I believe it’s called? My BIL got sent there and we’re still waiting on being able to talk to him but have been getting some letters. Today we received a very scary one saying he’s going to be knifed and “r worded” (censoring for people’s comfort) bc they found out his charges I think (I was read the letter by my crying partner so it’s a bit hazy) and I’m sick to my stomach. Is that something we need to worry about? Could it just be a scare tactic to try and intimidate him? I see so many mixed opinions saying “it’s nothing like movies everyone’s dramatic” to “it’s exactly like the movies good luck to him” but honestly that’s probably just everyone’s different experiences. We told him the basics of keep your head down, don’t start anything, be as respectful as you can but to not be a push over, ect but honestly who knows what he’s doing we don’t see/hear everything Yanno? He did alright in county but now this? He still has 2 years and 4 months I don’t know how to help the family during this if this is going to be his life. But to sum everything up can anyone tell me what it’s like in there? Is there a chance they’ll move him somewhere else? What can we do? I’m thankful for anyone who can answer even just 1 of these questions. Sorry for such a long post as well.