Dag,
Wow, that's unbelievable. That URL above *looks* long, but it's actually not too out of the ordinary for a lot of different features with JFBConnect and many, many other extensions. No one would ever type that URL in directly, but for automated and redirect type stuff for data, it's not uncommon at all.
I'd definitely get in touch with your host and ask what they are thinking and what proof they have that that in any way helps with security. I don't believe it and don't see it. There's plenty of 'bad' things that can be done in really short URLs and plenty of 'good' things that can be done with long ones. For note, I believe the longest URL supported by Apache is like 2000 characters.
Anyways, thanks for reporting your findings, and I hope you get that worked out with your host.
Alex