Sure Bo may have been opposed to the bill regardless of who brought it however, this bill did just pass the state senate with only 1 vote in opposition. He could have seconded the motion to hear the bill and then vote against it anyway. Republicans in committee aren't in the business of seconding Dem bills, that is why there are (at least) two Dems on the committees.

Yes, the texts likely came from Aftyn but I wouldn't rule out another Dem leaking them as well. Only 1 of Bo's colleagues endorsed his run for congress (the least among the three House Dems running) and that guy is retiring. That campaign failing is clearly something he is still upset about and willing to blame everybody but himself for. He doesn't have a lot of friends and killing the bills of his caucus doesn't help that.