No, the SC said the federal government can't outright ban sports betting. The logic was that a ban interferes with states right to legalize sports betting.
(To be clear, it is still an nonsensical decision though. Congress does still have the power to regular gambling under the interstate commerce clause, just not outright ban it)
I think it is a inconsistent position that the federal government can regulate gambling but not ban it.
The Controlled Substances Act also rests on the interstate commerce clause. Can you imagine if the federal government was allowed to regulate heroin sales but not ban it?
My question wasn't so much about the contradiction between regulating & banning authority, but questioning the authority to do either in the first place. I.e. I don't understand why gambling must necessarily be considered to be inter-state. But I now think this is unrelated to the point you were trying to make.
I agree that the broad reading of the interstate commerce clause seems dubious, but the same precedent [1] underlies the controlled substance act, clean water act, violence against women act, endangered species act and a whole lot of other laws. Unless you are willing to hack away a large chunk of US law, you can't really undo that one.
[1] Wickard v. Filburn ruled that growing wheat FOR USE ON YOUR OWN FARM can be regulated as interstate commerce because otherwise that demand would tend to raise prices on a interstate grain market.
(To be clear, it is still an nonsensical decision though. Congress does still have the power to regular gambling under the interstate commerce clause, just not outright ban it)