Stingrays don't care where the provider's towers are, they work by pretending to be their own, and (ideally for you if you are the person wielding one) causing your target's phone to connect to or through your antenna. The only way Starlink would help a target is if your phone rejects tower signals that are not mostly above you, or if Starlink Mobile would utilize something other than the 3GPP standards, both of which are unlikely unless they want to sell their own fully proprietary phones.