There is a variety of tests, their number grows all the time and some of them are specific to particular gene pools. Prenatal tests for more than 800 genetic disorders have been developed.
For a common example, people with Jewish Ashkenazi ancestry are tested for Tay-Sachs, others are not.
I ask what do people actually do, and what do people actually protest. Army can at least answer the second question. Non-invasive tests for Down's weren't even available before a couple of years ago. Your link appears to be about extensions of that technology, not anywhere near availability. Yes, Tay-Sachs is tested via CVS or amnio, but usually not all Ashkenazim, but only after screening the parents.
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.