I'm not defending all of Shaw's ridiculous critiques of Python 3, but the Turing-complete thing was a joke.

The conversation, IIRC, was something like this:

ZS: Why can't I import or translate Python2 into Python3?

P3: That would be a technically challenging thing to do.

ZS: But surely it is technically possible, even if it is pragmatically unfeasible?

P3: We can't do it.

ZS: OK, Python 3 must be Turing-incomplete, ha ha ha!

source: https://learnpythonthehardway.org/book/nopython3.html