As a Texan, the same question came to my mind: “What took you so long?” This has been going on for 3 years!
But I think one or more of your suggested reasons is the answer. Abbott needed to make the northern blue cities feel the pain before he could act. (Full credit to DeSantis who bussed illegals first.) Now that the invasion is recognized as the number 1 problem facing the US, Abbott’s actions are winning in the public arena.
Does PINO Joe want to go toe to toe with Texas in an election year?
Maybe. Maybe that’s the plan. And maybe after a bloody encounter his puppet masters will pull Joe out at the last minute and put Big Mike on the ballot in his place.
Then Michelle can distance herself from the “Recent Unpleasantness” during the election (No clue what they will do with Kamala) and the regime has another object lesson for the rest of the country.
One thing is for sure. We are living in interesting times. (See ancient Chinese curse.)