It's more a matter of how would a governor stop it?
The Federal Government will proceed. These governors need to know what their strategy is to stop them if they intend to do so.
Personally, I think it's all bluster for political effect as I don't belive any governor will call out the state police to stop a Federally contracted bus carrying nascent terrorists.
They just won't do it because they know in a day that bus will be escorted by National Guard troops that have been Federalized.
OF COURSE we need to force the Feds to do this at gunpoint.
But I don't think any of these governors have the guts for such a showdown.
With 26 governours and counting, they may find a backbone.