A 500 indicates that the server is there, but the request caused an unhandled error. Something definitely went awfully awry with their page, which, by the way, does not appear to be a wordpress page. Judging by the response headers, the server at least claims to be an ASP.NET server. I’m not quite sure why anybody would build a simple website on ASP.NET, but stranger things have happened.
In any case, considering the nature of the error, the fact that it seems to be built on ASP.NET, and my general experience in these matters, my best guess would be that the database is shot.
No biggie, especially for something simple as a website. It might just be that the DB is alright but the server currently can’t connect to it because somebody updated the connection string and made a typo (very easy thing to do in ASP.NET. Like, seriously, I hate those connection strings), or if the DB is gone for some reason, they’ll have backups. Presumably. Because everybody should.
At the end of the day, this is nothing to worry about. Happens all the time.
Aaaand… the forum automatically converts all my references to ASP.NET into hyperlinks. Is this forums framework written by microsoft, per chance??