I think it's telling that in contexts where consensuality is even more immediately critical, the social norm is for direct and clear communication.
awkward social burden of providing unequivocal rejections
It's unreasonable for people to assume the awkward social burden of subtle second-guessing, with the consequence of being labeled as a deviant if you don't. How is that any less unpleasant and corrosive than women having to second guess how they dress, or be thought of as a sexual target? Both of these situations needlessly eschew clear communications for illogical reasons, and hold starkly severe consequences for not adhering to them -- way out of whack with the cost/benefit analysis of avoiding a little "awkwardness."
I have also been gender neutral in my pronouns because I'm a guy, I've been asked out by women I did not want to go out with, and it was awkward, and it would have felt worse to just say a simple "No, I'm not interested". But she picked up on that just fine. My point is that there really isn't much second-guessing required. If they say yes, then you're good. If they counter-offer with a different time, you're still good. If they say anything else, that's no.
I associate this degree of social/mental gymnastics with Victorian England or the antebellum South, not rational people in 2016.
Given the number of people directly disagreeing with you here, I think you need to reevaluate your premise.
I like "no means no" as a principle. I wish everyone stood up boldly for the right to say "no." Do this by boldly saying no. The right to say yes but really mean no is something else entirely, and is corrosive to the right to say no.