I don't think that's an accurate portrayal that they were "C++ programmers" as if to imply they were experts or even proficient at it. Plan 9 doesn't even have

I don't think that's an accurate portrayal that they were "C++ programmers" as if to imply they were experts or even proficient at it. Plan 9 doesn't even have a C++ compiler. From his wikipedia bio, Ken Thompson "later refused to work in C++". I think they were surprised that C++ programmers didn't like Go because Pike and Thompson weren't actually C++ programmers. Griesemer however appears to know C++ well.