Any kind of utilitarianism entails every statement of the form "p, if it results in measurably maximized utility" (kinds of utilitarianism differ in what they mean by "maximized utility", since the phrase itself is underspecified), and I find it a bit disingenuous to instantiate p in a way that people wouldn't like in order to defame its proponents instead of saying straightforwardly that you just don't agree with utilitarianism.
Which is quite a different question from that of whether a given p does, in fact, result in maximized utility. Not idea if the above one does. So cousin_it's question makes perfect sense: does p in fact result in maximized utility? Because if it doesn't, then the blogger's statement is even more disingenuous.
I don't think that gets at the core of the criticism.
I think the position is: "You shouldn't be allowed to argue that policy X is good in the abstract scenario A if policy is is dangerous in the world in which you are living B and the fact that you argue that X is good in A increases the chances that X will be adopted in B."
A long blog post explains why the author, a feminist, is not comfortable with the rationalist community despite thinking it is "super cool and interesting". It's directed specifically at Yvain, but it's probably general enough to be of some interest here.
http://apophemi.wordpress.com/2014/01/04/why-im-not-on-the-rationalist-masterlist/
I'm not sure if I can summarize this fairly but the main thrust seems to be that we are overly willing to entertain offensive/taboo/hurtful ideas and this drives off many types of people. Here's a quote:
The author perceives a link between LW type open discourse and danger to minority groups. I'm not sure whether that's true or not. Take race. Many LWers are willing to entertain ideas about the existence and possible importance of average group differences in psychological traits. So, maybe LWers are racists. But they're racists who continually obsess over optimizing their philanthropic contributions to African charities. So, maybe not racists in a dangerous way?
An overly rosy view, perhaps, and I don't want to deny the reality of the blogger's experience. Clearly, the person is intelligent and attracted to some aspects of LW discourse while turned off by other aspects.