The Antfia people ship supplies across state lines and have support networks that go from state to state, all with the intent of committing crimes.

That wouldn't give the feds jurisdiction over the case absent a specific federal crime. Again, the crime has to cross the state lines. Not the supplies.

You quoted the riot statute, which does create a specific federal crime. But it's a very hard one to prove. You have to prove more than just people shipping supplies for protests, even protests that are likely to result in a riot. You have to show that they specifically intended that the supplies be used in a riot. Which is very, very hard to do. And that statute wouldn't be applicable here, since none of these campus incidents have been "riots" as that term is used in the criminal code.

Antifa and what they do fit the very definition of this law.

Again, no. A national group supporting local groups with supplies (or organization) doesn't satisfy that law. Even if the local group were to go out and commit a riot with those supplies. The individuals in the national group need to be proven to have: i) intended that the supplies be used in a riot (not just to help the group in any other way); and ii) have themselves personally taken an overt act themselves in furtherance of the riot. That first one is going to be almost impossible to prove, and the second is exceptionally unlikely to exist in the current situation.