On the compassionate post, I don't think there was ableism, unless there's a disability that hinders people from compassion? Conflating compassion and empathy may be a problem for understanding, but I don't think that's what happened.
There isn't a disability that hinders people from compassion in and of itself, but there are multiple ones that hinder empathy, and compassion and empathy are often treated as synonyms, so in the post, it wasn't clear which OP actually meant. If OP meant simple compassion, then there was no ableism (that I can tell), but if they were treating compassion and empathy as one and the same, then the post was ableist. It all depends on the context, I suppose.