Well, it's quite simple really - the license is not GPL and there is no reciprocity requirement - that alone in the minds of some GNU fanatics, amongst which obviously Moglen is, is a crime against freedom and all that's holy.
Maybe I'm getting old, senile and cranky, but thing's didn't use to be this kooky in the open source movement, did they? I mean, there was always the political component to it, the strife for influence, the "stick it to the man" thing, but things didn't use to get this out of hand - smearing another open source project, simply because it's kicking your ass while having a more liberal license.
The FSF has always been this political. Open software has gotten less political over the last 15 years.
Moglen doesn't think non-copyleft software is a crime. The evidence suggests that he thinks non-copyleft software is bad for free software in the long run, because it has the effect of enhancing non-free software along with free software.
Anybody can observe that over the long run, if most of the best work in open software is done without copyleft, copyleft-protected software will suffer; free software will have one major contributor (people writing free software), and nonfree software will have two (huge companies and people writing most of the best work in free software).
It's not complicated. It's a reasonable perspective. Disagree with it all you want (and I do), but it doesn't deserve to be mocked.
The reciprocity is in there to ensure free software stays that way and that any improvements made to it don't end up exclusively in proprietary versions. I think, as a user, that it is better at protecting my interests and that it's better to protect competition by commoditizing the software.