I fail to see the point, tbh. I've always found such distinctions more illusory than real. The way I see things not taking an action is a choice (ergo an action) in itself, and often comes up in difficult dillemas as a way to wash your hands off a problem. In the question at hand, a zygote will unavoidably become a person... unless it doesn't, for a thousand different reasons, external or internal. It hardly serves as an argument about the zygote's personhood, or the rightfulness or wrongfulness of contraception. By the way, I don't consider the argu,ent from potentiality (which closely mimics this) as inherently religious, but just like in this one, you have to accept the premises, which I really don't.
There're also further consequences from these kind of reasonings when carries to their logical conclusion. For instance, I heard a bioethicist (my uni bioethics teacher, as a matter of fact) argue that in the clinical dillema of separating a couple of cojoined twins sharing vital organs to save one of them, the moral thing is to abstain and let them both die. With which I strpngly disagree.
A more recent and real, not hypothetical, example: I've been present in argument arguments about curettage in pregnant women with leukemia, with some people arguing that treatment should not be administered because it would be deadly for the foetus. Nevermind that there is not a chance in hell for the pregnacy to come to term.
(For the record, in those cases I was present we did carry out the treatment in the end.)