If this is not a joke, it might actually be a viable idea. It works pretty well for English text, for example:

https://arxiv.org/abs/2305.15047

And, although I suspect the original comment was made sarcastically, not at all at odds with the reasoning why they would reject submissions with AI generated code.

I think ultimately text is too structured by itself to be able to understand whether it's AI-generated or not. You can easily tell LLMs to write in a different style or even give examples, and they'll happily oblige. Those tools are mostly useful for filtering out the laziest users who haven't tried playing around with the models enough.

I am interested to see what Google has developed with SynthID to be able to watermark text.