The choice of protecting money is a strategic one, not one of judicial sobriety. And as we expect from that kind of ruling, it falls exactly along the political lines of the appointing president.
It is an extrapolation to suppose the founders intended allowing every avenue of distribution regardless of outcome. It's just as (un)clear the founders would be appalled at the current tight feedback from campaign finance which in many cases is indistinguishable from bribery.
First ammendment absolutism in the face of rapidly changing technology is way more tiresome.
Maybe the reasonable answer is that you shouldn't, especially in the face of rapidly changing technology, which nowadays gives us huge choice of what to look at. The example of outdated censorship doesn't make a valid argument for more restrictions.
This doesn't mean Facebook couldn't ban political ads, but it does mean it would be unreasonable for the government to do so.