[hnbad]

You're conflating the two things I said. The pill interferes with the menstrual cycle to prevent ovulation and, usually, menstruation. The morning-after pill acts similarly in that it interrupts ovulation but additionally prevents any blastocysts from implanting, yes. That's why I'm saying it's usually the rhetorical gateway when trying to attack contraceptives before doing so is rhetorically viable.

A blastocyst has 200-300 cells, yes. But if you hadn't stopped reading the Wikipedia article (or high school biology textbook) you'd have noticed that it also says that a blastocyst begins to form about five days after fertilization and implants two days later. Also even without chemical intervention only 30% of fertilized eggs survive to develop into blastocysts and successfully implant -- with implantation failure being the most likely outcome even if the fertilized egg develops to that stage. A lot of the lead-up treatments in IVF processes only exist to ensure that a blastocyst can develop and sucessfully implant itself.

Note that the literal "morning-after" pill (effective within 72 hours after intercourse) available over-the-counter in most countries including the US often only contains a progestin, i.e. it's just a higher dose equivalent of the regular pill. What you are talking about are pills containing an antiprogestin, which indeed can also act as an abortifacient, even though I've never heard any medical professional refer to a failure to implant as an "abortion".

That you're conflating all three of these pills (the Pill, the OTC morning-after pill and the one containing an abortifacient) is a good demonstration of the "incremental contraceptive ban" strategy I described.