No, the argument is that you should believe the value of vaccinations, and that disbelieving the value of vaccinations itself makes your parenting lousy.
Which is pretty much the same argument as saying that you should baptize your children and that disbelieving the value of baptism itself makes your parenting lousy.
If the belief-set you're subtly implying is involved were accurate, then it would be.
However, I think we have a "sound" vs "sound" tree-falling-in-the-woods issue here. Is "lousy parenting" a virtue-ethics style moral judgement, or a judgement of your effectiveness as a parent?
Taboo "lousy", people. We're supposed to be rationalists.
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.