Amanda points out the obvious:
Here’s an interesting double standard to think about—if a radical feminist says that blow jobs are displays of subservience, then all hell breaks loose. But if you praise blow jobs as a female duty paid to male superiority, then that raises nary a peep of protests about “man-hating”

Because the first disturbs the status quo by pointing out stuff that is supposed to be hidden. It's nice that there are exceptions to the rule, but how likely is it that this is being conveyed to people when their basic conceptions of sex and how the world has to be is being formed? The idea that men are owed blowjobs for existing is pretty pervasive in this society, and you can't break that down by putting your head in the sand and saying "but my Milton gives head!"