If that theory was correct, one might expect Forth to be really popular among Japanese speakers. I don't see a lot of evidence for that.
I tend to think it's a more general effect where humans actually want a certain amount of irregularity in their languages/notations, to act as markers or error-detecting codes of some sort. e.g. "he", but "him" in accusative case. But who knows; English gets by with "you" being both singular and plural...
Theory: people prefer infix to prefix or suffix notation because it more closely mirrors the Subject-Verb-Object patterns of their native languages.
Corollary: lisp feels awkward because it doesn't map cleanly to native language thinking.
Lojban is mostly SVO as well.