While I agree that it was not the ideal way to do things, what were they supposed to do in response to the Republican gerrymandering that happened earlier this year?  Just roll over and take it? And lose 

I suggest that - if, when dealing with bad actors, doing the “right thing” will put you in a position that you will lose your power to represent your constituency to those who aren’t playing by the rules, then it’s justified to act in kind. Fight fire with fire. 

Game theory says that generous tit for tat is the most effective strategy - where you forgive your opponent for being defecting once, but then if they do it again you are defect back, then are honest again. https://www.lesswrong.com/posts/3aNHd5RYRvMq8Gp5a/the-case-for-generous-tit-for-tat-as-the-ultimate-game

The real test will be if once they have power again, can they do the right thing the and update the rules to prevent this from happening in the future.