You seem to have the restrictiveness backwards? The MIT license (uutils coreutils) is less restrictive than the GPL (GNU coreutils), and the AGPL is more restrictive than the PostgreSQL license.
And it doesn't violate the PostgreSQL license to license the rewrite more restrictively. That's part of what makes MIT-style licenses less restrictive than the GPL or AGPL: they allow for more-restrictive relicensing.
Perhaps ‘restrictive’ was a poor choice of words. ‘Less free’ in the free-software sense.
I’m still putting together my thoughts on various open source licenses especially as we see automated AI rewriting.
I think licensing will have to be re-invented, because now it's trivial to just say: claude, do a "clean-room implementation", so that noone can accuse me of stealing code.
That's what LLM companies have done for years anyway. Inline completions are trained on licensed code. And nobody cares! ;)