Pitman said that compilation of FEXPRS is difficult. Even with lexical binding. Pitman argued for a macro expansion phase. Etc. If you read the original kernel paper it does not even discuss Pitman in more than two sentences. Since Pitman is still alive, he could have even asked him. The kernel paper had a seperate addendum where vague ideas about compilation were discussed.
Pitman was working on large software systems where compilation was the norm and useful.
All the references to lexical scope but one are annotations added decades later. The one early reference said "dynamic scope harder than lexical scope."
In any case, the claim that fexprs make compilation challenging for large software systems is much more nuanced than what you were implying earlier, that Kernel's no different from "the 1960s".
Now that compilation is less challenging thanks to lexical scope, and with computers being so much faster, it's worth considering whether fexprs can be compiled to be fast enough (say to ruby levels for a start). That would still be valuable. Right?
I think it's very superficial to claim that only 'two sentences' of Shutt's thesis were about 'Pitman'. He mentioned the concerns in the abstract[1], for crying out loud. He's addressing the issues throughout even if he isn't constantly paying homage to some sort of Pitman deity.
Pitman was working on large software systems where compilation was the norm and useful.