If I understand his allusion properly, I don't think Francis accurately characterizes the position of those who were in favor of letting Charlie Guard die. It didn't seem like anyone regarded "the disappearance of a person as a good thing."  One may find the compassion of those making the decisions ill considered, or mistaken in its object, given that it ran contrary to the wishes of Charlie's parents, but that doesn't mean it wasn't compassion. 

Compassion need not always yield the same result materially. Sometimes it yields awful results, when those acting from compassion have insufficient understanding. But it is still compassion. This points to the hazards of acting from sentiment. Charlie's parents were unsurprisingly motivated by sentiment, but the judgement of Charlie's advocate was that if they were allowed to pursue their hope, the probable consequence would only be an increase in suffering, both in intensity and duration, for Charlie.