I'm not sure whether you asked them to wait at the end before typing detailed information but unless someone asked me specifically to stay back, I wouldn't have done so. Also I don't think trying to make them change their rotation mid-run would have had the desired effect as it would have had the effect of singling them out (plus changing your rotation even if it's wrong isn't something that can be done on the spot). I suppose you could ask generally if people are okay to use AOEs or you pull less and that would have given a hint and potentially a start at a conversation.
BLM especially if you go just by the tool tips can be very misleading as the raw potency of the lowish level AOE spells is small. When I started playing BLM a couple of months ago, I remember thinking they aren't worth it and it took someone to actually point to me that there is a specific rotation that needs to be done to get the damage out. Funnily enough that person actually asked me to stay at the end of a run that I thought I was doing really well and explained about the rotation. I'm grateful he didn't try to do it mid-run as it would have been too embarrassing. Also I've only levelled up BLM up to level 60 so far, so I need to pick it up again.
In all it's okay to talk to people provided they want to listen but it takes some work to make it work.