I do think that deliberately making others feel uncomfortable is rude. It is certainly understandable when the person was rude, especially deliberately rude, first, and sometimes even justifiable when the provocation was realy extreme -- like a bigoted slur. And notice that Miss Manners did say that saying "Thank you for reminding me" would be rude.
This is certainly a thoughtless thing to say. But it's far from certain that anyone saying it means to hurt the OP; they are probably just lamely trying to be sympathetic. That's not so easy, especially when it's not an experience you've had yourself yet; look how many posters ask what to say to someone bereaved. I don't think it really deserves an icy rejoinder, although I certainly understand the impulse.
We've all been in both positions, I think -- saying the wrong thing when we mean well, and hearing stupid, even painful comments from people who just don't know enough to keep it to a simple "I'm sorry." You wouldn't believe the things I heard when I had a miscarriage and when my father had (and died from) Alzheimer's. Well, yes, you would, if you've been in a comparable situation. It took a lot of self-control not to react.
But what would it have accomplished? I knew they all loved me and were just trying -- and failing -- to say something comforting. Smacking someone down for a blunder doesn't help anything. I think people learn better when someone takes them aside privately and explains why what they said is actually hurtful and suggests something better, or, if an in-the-moment response is called for, says something like, "I know you mean well, but that's actually not very helpful. But thank you for your sympathy."