Since a lot of people either didn’t read or can’t read. This isn’t a Supreme Court ruling on the substantive issue of gun kits and their legality. This has an interlocutory posture, which is sort of like saying the higher court has weighed in on one aspect of the case (the lower court injunction) while the appeals process is still ongoing.
TL;DR - A lower court stopped enforcement of a federal regulation. The Supreme Court said it can be enforced while the underlying issue is still being litigated.