Did the USSC ruling hinge on these being abortifacients?
(I'm finding it slow going to find specific & reliable info on such aspects of the decision.)
If you want specific and reliable, you may want to go straight to the horse's mouth. You can find the actual Supreme Court decision here:
http://www.supremecourt.gov/opinions/13pdf/13-354_olp1.pdf
As to whether the ruling hinged on them being abortifacients... that's a bit fuzzy. It definitely hinges on Hobby Lobby's owners belief that these drugs are abortifacients. From the decision:
Since RFRA applies in these cases, we must decide whether the challenged HHS regulations substantially burden the exercise of religion, and we hold that they do. The owners of the businesses have religious objections to abortion, and according to their religious beliefs the four contraceptive methods at issue are abortifacients. If the owners comply with the HHS mandate, they believe they will be facilitating abortions, and if they do not comply, they will pay a very heavy price—as much as $1.3 million per day, or about $475 million per year, in the case of one of the companies. If these consequences do not amount to a substantial burden, it is hard to see what would.
I find this part of the ruling strange, since the belief that these four drugs are abortifiacients isn't really a "religious" belief, IMO. It's not like there's anything in any religious creed, scripture, or tradition that says "I believe that Mirena causes abortions, so help me God."
Rather, I see this belief about these particular drugs as a position about the facts of things, which in turn informs a religious view. The real religious belief here, IMO, is that abortion is wrong. That might be legally entitled to protection under either RFRA or the First Amendment, but the belief that particular drugs do or don't cause abortions should not be, IMO.