I don't really know much about the sweat baby controversy, but whenever I see "bless your heart" it just comes of as weak tea as it avoids engaging with premises or arguments and condescends and I think it generally loses the argument from a third party perspective. At least I've never read it and thought, wow they really got them.

It might be trite but I always preferred agree to disagree as a disengage tactic. That's just my two cents on internet discourse though.