What's showing is your ignorance. What you said only matters if it was Rivera's decision to bring them here in the first place.
why wouldn't it have been rivera's call or at least why wouldn't he have had a hand in it? they needed help at RG. MJG became available and they moved in. they saw that hangman was available and they moved in on him as the better choice.
MJG was a sure bet as far as being able to acquire. hangman, not so much because he could go wherever he wanted and there were other teams interested. he wanted to come back here.
as has been said by level headed people plenty of times, there is a chance that there is something wrong with the guy, having been let go from not just one, but two teams so far this year. it was worth a shot to see if he could fit the need.
also it is very possible that they just don't want to give him, who will be a backup, guaranteed money so they will pick him back up on monday.
there's no reason to rage. there's no reason to go feeding some kind of "I HATE HURNEY!!!!!!" campaign, unless you just can't control your emotions and you just can't look at a very possible and most likely scenario other than "hurney just thinks with his gut and makes calls based on emotion".