I would rather hope that after someone has given birth she is no longer protected in law from discrimination against her on the grounds of pregnancy! Otherwise any woman who has ever had a child (living or dead – would miscarriage count?) would continue to be protected against discrimination on the grounds of something which no longer existed, which would be absurd.
Likewise if someone ceases to be a Scientologist, say, or a flat-earther, or a Branch Davidian, they certainly ought no longer to be protected in law from discrimination on the grounds of their belief in something they no longer believe in.
I reserve the right to be put off someone pregnant who swears at my children and throws litter in the street, just as I feel entirely entitled to dislike and avoid a member of any religion who sidles up to me in a public place and asks me unctuously "are you saved?" (Or come to that knocks on my door when I am cleaning the bathroom upstairs and drags me from what I am doing in order to ask me a similar question. It isn't because of their religion that I wish them to Gehenna, it is because they are a pestilential bloody awful nuisance, and unctuous with it.)
My objection to mandating special consideration for one of a nebulous group of people who are in actuality impossible to define even in the abstract, let alone in a shop, remains the same: if I don't know someone, how can I manage not to do what every human being does automatically in any meeting with another human being she doesn't know, quickly judge that person as to whether he or she may present risk to me? I'm sure you discriminate at every single encounter with everyone, quite unconsciously: it this person drunk or not? Is this person angry? Does this person have a lovely smile? Is this person in distress? Does this person look lost and in need of help? Is this person clearly very strange, and worth giving a wide berth just in case? And so on and on, all in a split second.
Discriminating, after all, is not always a negative thing to do. When I was a child and wanted something my mother recognised as utterly inappropriate (a thick jumper on a hot day, for instance) she would say "oh, for heaven's sake show some discrimination!" The ability to discriminate between safe and dangerous is a survival trait.