I'm confused how that's related, the issue you're talking about is in the file manager, not GTK. I don't believe any of the primary nautilus maintainers are also primary GTK maintainers, at least not anyone in that issue. (Please correct me if I'm wrong about that)

But, since I've said this before, I'll say it again: If the other people who use the toolkit want to have input, they need to contribute more. AFAIK there are zero non-GNOME devs working full time on GTK. I hope that changes, i.e. I hope the other desktops can find funding to send more designers and developers to collaborate with the GNOME people so everyone can have their say. That is the real issue here, I think it's incorrect to suggest that anything was "taken." It's open source, there isn't anyone who's going to take the code away from you unless you blatantly violate the license.