It just means that the partisan party has made a litmus test out of belonging to the hated non-partisan organization.

I was a member of the NRA when I was a Democrat. I'm not a Democrat any more, but it had nothing to do with the NRA. Neither the NRA nor the ACLU have kicked me out for belonging to both organizations, either, though they don't like each other much. That's because they're both non-partisan, even though they both have their organizational agendas, and have both been "adopted" by partisan groups.

At some point, whenever I point out the overload of Democrats in a particular group, like academia or the press, the people I am arguing with usually retreat to the idea that of COURSE more Democrats would be there, since they are prima facie, better, smarter, more perceptive, more sympathetic, and more reasonable than Republicans. End of discussion. Hasn't happened here yet, but if the thread kept going, it would pop up sooner or later.

Of course it has popped up. You popped it up. Were you so worried that it wouldn't pop up that you had to do it yourself?

Sounds to me more like you resent Democrats than that you think that non-partisan is just partisan in sheep's clothing.

If you wanted to belong to the ACLU, because you value civil liberties, would the Republicans de-Republicanize you? Democrats looked at me a little weird over the NRA, but when I explained my approach, they conceded that I had a point and didn't call me names.