.....Not going to attempt to debunk the Facebook group discussions...they are what they are...rather I am going to provide what I know to be true and factual.
Back in the 70's - 80's there where perhaps hundreds of thousands if not millions of plastic ash trays. Plastic being the kissing Cousin of resin shares some of the same chemical make up, mostly petrochemicals. The only way that the toxic stuff could get released was if the ash tray , itself, was set on fire and not from a smoldering cigarette, cigar, etc.
I have some chunks of resin (RC-3) that I used for this experiment.....here is my findings.
Since I don't smoke, the only source of heat that I needed, that I could think of, was my soldering iron. The soldering iron generates less heat than the Cherry on a cigarette...... 752 degrees for a cigarette in an ashtray verses 600 to 650 for the soldering iron.....I think that at this point that 100 degrees is probably negligible.
I pressed the soldering iron against the chunk of resin. It took around 3 minutes of pressing against the resin chunk before a very small wisp of smoke came from it. A burning cigar or cigarette is not in direct contact with an ashtray for that long.
To get the resin chunk to release what I would consider to be toxic smoke , I had to set it on fire. The smoke was the same Black smoke as if you set a piece of plastic on fire...the burning petrochemicals.
I will add this....since most normal people don't go around sitting ash trays or resin on fire, there is a much bigger health risk with the air we breath sans any smoke at all. The outside environment is chocked full of hazards in the form of naturally produced pollen, mold and dust which in my opinion are much more hazardous than resin in its normal state.....whether cured or uncured.