True. But that same sentiment can be communicated without trying to corral developers into two arbitrary groups. There are plenty of other reasons, in addition to the lack of a substantial number of Objective-C (not just iOS) developers. One of the reasons, I think, is a distinct lack of notability for GNUStep.
Anyway, this is a pretty silly line of disagreement. :)
But that's exactly what I've observed: nearly all ObjC developers fit into one of those two categories, and that's why roughly nobody wants to bother with GNUStep. I suppose I could have made some different point instead, but I'm generally going to make points about the stuff I've seen.
Perhaps the reason those ObjC fans of the language itself seem to be smaller in number by your metric is that there are other reasons for avoiding GNUStep--namely, that it's GNU. If you've grown up with OSX etc., then you're more likely to be BSD type person (thinking primarily from a licensing perspective here), and the FSF's push viral "software freedom" is a big turn-off.
Anyway, this is a pretty silly line of disagreement. :)