Foxworth was convincing as an unfinished android. I think they made the right choice.
Foxworth is a better actor than Nimoy.
To be fair, Roddenberry threw a fit about Meyer's original plan of making Saavik the traitor because he didn't like the idea of such a popular character betraying her shipmates. Meyer told him, "Well, I'm the one who created the Saavik character, so I can use her however I want. If you have a problem with it, then maybe you should give back all the money you made off the films I was involved with. Then I'll care what you think."
I've heard this before and always found it a bit contemptuous on Meyer's part. I agree that it was probably the right thing to do and the she was his character and he could do what he wanted with her, but the whole "give back the money" bit, aside from being douchey, is asinine and presumptuous.
For one thing, had it not been for Star Trek
, Meyer would still be a hack nobody. And, frankly, outside of Trekdom, he is
a hack nobody.