I think the episode covered all 5 stages of grief quite well but the overall weightage of implied death was IMHO not enough to really strike the heart so to say. The overall message seemed to be more relatable to people who have gone down the same path before but it feels like a somewhat not-quite-there attempt to intoduce the concept to members of the audience who haven't. Maybe it is just me but I was actually leaning towards the following during the episode:
1) RD taking a natural occurence and blowing it out of context
2) Refusal to listen to advice of friends with credentials (fluttershy is somewhat valid as an anthropologist) and seeking phony corroborative evidence (spike) to back one's false confidence actually flashed more anti-vaxxer/anti-stuff concepts than the grief message of the episode
3) Damage to property including causing potential risk of death to the workers at the cloud plant. Being an engineer here really hit some strings that she was not accountable at all for her actions and really put all the plant workers lives at risk. The should make her visit a hospital next episode to show that her actions affected someone else.
The episode would definitely be better and much darker than some would like it to be if Tank had actually died as I think everyone would understand the overall message. Then again, this is a kids show with GoT references so maybe I am just looking a little further than usual.
+1 because AJ cries inside. We all do AJ.