The GPL school is definitely in the passive-aggressive means of control camp. They don't want freedom unless it's their brand of free.

Disclaimer: IANAL. That said, I think part of the reason to enforce cases like this is that if this clause in the license goes unenforced for long enough with the IP holders not suing, then it becomes an implicit rewriting of the "must provide source" part of the license, and then weakens any later legal case.

I agree, the provision to provide a tarball of source is silly. It probably made more sense in the days of semi-disconnected FTP sites before http and Google made everything so much more discoverable.