Having come under more than my fair share of unwarranted and vicious flak - most of it from anonymous posters with multiple identities - I'd be the first to agree that somewhat tighter control does need to be taken by the moderators when postings get to the libellous level.
Should PPRuNe be shut down, though? No way! This is an informative, very often amusing and frequently highly relevant forum.
Through PPRuNe, I have encountered some of the most interesting and helpful people I know. I've had many great days and evenings with them; and a number have worked very closely with me on various projects.
Danny and his team, on balance, do a first class job considering that they all have 'day jobs' and are unpaid for their huge efforts.
As for the often blatant nationalism - I think we're all guilty of that at various times ... certainly I have been very voiciferous in my opposition to non EU airlines (and crews) operating within the EU and taking EU pilots' jobs. Is there anything wrong with that?
Long live PPRuNe!