That is very well put. Had I been in the discussion, I would have argued strongly for “Slack style”. Recognizing that Discourse Reactions is “Facebook style”, this simple Facebook-vs-Slack style of reactions is the cleanest, clearest way to express why it would be good to stop describing Retort as simply superseded. Retort being maintained or replaced does bring up all the dilemmas around limited volunteer (or paid even) developer hours and priorities, but I think everyone being clear about the situation is a start.
FWIW, too late now, the existence of Retort being “Slack style” could have been brought up as a reason to make Discourse Reactions that way since it would be a smooth transition for everyone already using Retort. As is, we can treat this topic as a request for a “Slack style” plugin, an actual successor to Retort.