Well it isn't our Forum is it? It's run by the Moderators and they have every right to sort it out as they see fit. 'Their house, their rules' etc.
Also, as I see it, sometimes the nastiness on a thread gets so appalling, the only thing to do is to shut the whole thread down.

One wants to encourage new members and posters, but imagine the reaction of someone new coming on here and seeing all the rude, insulting and disgraceful bickering, the political back-biting and personal insults etc. They'd probably shove off pronto and look for another site.