It's not hard to see the Rangers taking the senior BLM guy in Texas into custody for his own protection.

Yes, it may have been about some deal Harry Reid was hustling.  It was also a dry run for armed federal agents, who BTW aren't sworn to uphold the Constitution, to bully and tyrannize a citizen.  It could have turned out to be a Waco or Ruby Ridge atrocity.  But BLM found out that they couldn't get away with it in broad daylight, even with the Sheriff sitting it out.  So they will go back to the drawing board.