My point stands, there is a huge gulf in the US and Canada, UK (smaller experience with local feta there but it wasn’t good) etc. I wouldn’t support a GI limited to Greece , edited to clear that up.
I suspect we are making compatible points - you that other countries exist that make good feta by default (true!) - me that countries exist where the default is not good (at least to my taste) and definitely distinguishable from the former category (also true).
I guess feta is a good example of the problem of defining these things by region not process. I feel pretty confident that "feta" shouldn't belong to any one country in the region with a tradition of making it; on the other hand differentiating it from cheap knock offs also makes sense to me.