Sorry, that's a straw-man. As there are very few pro-life athiests, this is very, very unlikely to happen.
First of all, "very few" doesn't equal zero. Secondly, as an example, over 20% of self-id'd homosexuals voted for Pres. Bush. You can't stereotype every atheist or every homosexual according to your pre-conceived idea of what every atheist believes. You can speak of generalities and be generically true. That doesn't make it absolutely so.
You make it a "straw man" only because you choose to give no weight to what a minority of folks within a certain identity trait might believe and practice.
Just because most Mormons don't practice polygamy doesn't mean we won't one day have a polygamist Mormon run for public office somewhere. (Oh wait a minute...I guess there are certain mayors & city council members who already qualify under that description)