After all, the ad hominem rule is not some generalized prohibition against personal attacks. It is merely a prohibition against baseless or irrelevant personal attacks – especially when used to deflect a justified charge, skirt a legitimate issue, or evade a properly vexing question.
This is a very important limit, and one that serves a valuable social function. Specifically, it's what allows us to derive positive utility from clear and direct condemnation of dubious personal characteristics in cases where those traits are producing or defending overt violations of reasonable and openly defensible social norms – like not gleefully spreading baseless FUD, for whatever reason.
I'll be the first to agree that killing messengers is bad policy. That said, I'm also a big fan of marginalizing unreliable narrators. In that regard, knocking Assange down a few pegs seems like a major boon to the mass surveillance conversation, which could really benefit from cooler, clearer heads prevailing.
