I wasn't for an instant suggesting that the person who wrote that anti-Feynman screed was actually impartial, nor that they expected to be thought not hostile to Feynman.

But a theoretical physicist might have thought their attack would look less like a matter of professional jealousy if they couched part of it in terms of how much more appropriate an experimental physicist would be.

(I don't think that's very likely. I think the person who wrote this was probably not a theoretical physicist. That's why I think it was unlikely-ish to have been Edward Teller. I was simply pondering possible reasons why a theoretical physicist like Teller might have written those words about theoretical versus not-so-theoretical physics.)