Imagine the confusion between "Nu variant" and "new variant", when the next variant appears. Also, Nu is basically ungoogleble.
Bonus points: Nu is the 13th letter of the Greek alphabet, and today is Friday 26 (2*13).
Nu means naked in Portuguese (and Spanish I think?)
Maybe they wanted to avoid all the lazy puns. A pretty significant part of the world speaks either of those two languages.
Also in French.
Also in Catalan, but not in Spanish.
Or, you know, Xi..
That would probably get renamed the pooh variant.
Ha, didn't know there was a Xi between "N" and "O" in the Greek alphabet. I don't wonder why they skipped it.
Just guessing: Nu is too close to Mu. Xi is pronounced too inconsistently to be useful internationally.