The underlying issue is
a valid point - about as blatant as having the heroes encounter a starship with the name Nostromo
very visibly stenciled on the bows in Latin alphabet, beaming aboard, and being surprised that it's crewed by humans.
As a way of rationalization, we could assume everybody already suspected Data was a Soong creation. But since Soong had disappeared in disgrace, he couldn't be interviewed on the issue - and suggesting such parentage might actually have been considered embarrassing for the poor android.
Did Starfleet know Data was positronic, though? He seems willing enough to open up (quite literally!) to certain types of investigators, but had he actually done that before "Datalore"?
Giving an android the face of Soong would probably be a popular thing anyway. Much like giving an android today the face of Einstein or Gibson (Mel or William, depending).