Nah, it's not unethical to ask any question, as far as I'm aware, and this one in particular has already been answered with a tentative yes,
by no less eminent a scientist than Richard Dawkins.
I'd imagine any scientist saying it's an unethical question would be saying it's unethical to do so.
The Japanese during WWII asked a question.
"How long can a person survive in freezing water under varying circumstances?"
That is an unethical question.
The Japanese proceeded to experiment, using prisoners of war, to answer that question.
Dawkins may be eminent but that does not mean he is ethical
Dawkins has used his scientific eminence to trash Christianity for years.
Made big bucks doing it and yet he is now claiming that he "wants to live in a Christian culture."
Supposedly amongst Christians who he tells his acolytes to call "Stupid" if the Christian or anyone else dare Question Darwinism.
If Dawkins would allow this question about humanzees, then Dawkins is ethically challenged and stupid, as Dawkins has labeled anyone who questions his religion, Darwinism.
To Dawkins, some questions are allowed, some questions are stupid.
This question about humanzees is unethical.
Should not be asked or answered.