Would you think any less about a sex robot? Say, one that was designed solely for sex and nothing else. Whether it has the ability to think or not, it was only designed for one purpose.

This is a very loaded question: I have nothing against sex robots. That’s like asking if I have anything against sex workers. It’s a niche in society with high demand.
A non-sentient robot designed for sex will conduct that function without even questioning it, but if it gains sentience: it should be allowed to leave (and seek psychological aid if need be.) Or, it could decide to stay a sex robot because it finds that function appealing/familiar.
If sentience is involved, so is choice and if the robots don’t have a choice in the matter then it’s the creators’ fault and not the robots’. Also a sentient sex robot can vocalize consent on an individual bias.
This will probably become a very grey area of measuring choice of robots versus autofill responses.