The claim wasn't that they are unaware, the claim was that it doesn't seem to show in the design of Go.

I think Go is a perfectly fine language, and I respect the goal to stay clear of complexity, but when looking at any particular Go feature, then it's easier to explain the decision with "They are used to thinking in terms of C-idioms." than with any particular brilliance or awareness of PL-theory.

I believe it: Thompson is old enough and Pike is arrogant enough not to have learned the relevant programming-language theory.

Thompson turns 80 this year. In what years does Thompson become old enough that you start to entertain the possibility that not everything he says or does is the result of having learned and understood all the possibly-relevant work, including the recent work?

I misspent a few thousand hours of my life on the 9fans mailing list long ago when Pike was very active on it, and my non-joking assessment is that ever since he finished his PhD or shortly after, Pike has probably felt he knows all he needs to learn about programming-language design except for the things he and the people in his immediate social environment invent.

Bell Labs was never good at designing programming languages. Did you know that in the Bourne shell (and possibly in all the other shells) you can have a statement of the form $foo = bar which will assign bar to the variable whose name is the value of foo? (Emacs Lisp, an old language, has the same functionality in the form of a function named "set", but most Emacs Lisp programmers know to avoid it.) Well, I found that statement in a shell script written by one the Bell Labs guys, and the shell script was not doing anything fancy like interpreting a programming language or defining a new PL feature (not that it is sane to do either of things in a Unix shell).

None of what I say is more than a wisp of a reason not to choose Golang IMHO.

You're moving the goal posts. The claim isn't that Ken Thompson or whoever is flawless. The claim is that he isn't stupid.