My main problem with the “prank” is that it completely disrupted the help channel of another network for a long period of time. In fact the disruption still continues. I don’t think that the people participating in it would see the funny side if it happened to their channels.
The only channel I regularly visited on freenode was #lugradio so this is perhaps not a big deal, but unfortunately by being on the network it does imply a certain level of agreement with its policies.
By the way, it wasn’t even April 1st in most of the world when Levin initiated his “joke”.