It is good and reasonable to be continually skeptical of the people and organizations we get involved with, and I appreciate your warning and looking out for bad organizations.
On the other hand, my experience in politics leads me to believe that if you sit around waiting for the perfect allies, you will usually be waiting alone for a very long time.
Looking at this group, it looks like in my state (Utah) they have been key support for a couple of well respected local nonprofits that have done great work on RCV and anti gerrymandering. That doesn't sound like such a bad thing to me.
I think it's a mistake generally to view Republicans as the enemy. Even if they are in a leadership role like in the RNC. For example, in Utah, nothing gets done without Republican approval. So saying "I won't work with you because you're Republican" here is a losing strategy to make changes. And we now have the beginnings of progress on RCV.
So I think we should continue to be vigilant and watch out for the first signs that people are acting in bad faith. But if we want our ideas to be popular, we are going to need to learn to (without compromising our own values) build a bigger tent.