That is my reading of it too. SCOTUS said the BP has the authority to do essentially what they want on the border to do their job, but do not have the same authority to interfere with the actions of TX. Neither the BP nor TX can stop the other.
And whose to say that the Border Patrol will do anything to remove the wire anyway.
That is a very relevant question. My friends in the USBP were heavily in favor of the Texas move to fortify the border. One of those "'bout time" type conversations.