The super motley boa, correct?
IMO - it's up to the buyer to research and know what they are buying.
As a seller, I would disclose known issues. In this particular case where the super is known to have longevity issues*, I wouldn't even sell it (wouldn't do the breeding that produced it either) but obviously this specific seller doesn't share that viewpoint.
*most die within the first two years, I do know someone that had one live over 5 but I don't know what ended up happening with him, I assume he passed.
For example, I was interested in picking up a mimosa. After further research I decided to pass since finding out champs can wobble. No one discloses that in the ads. It's up to the buyer to research.
Posting a warning on someone else's ad is in rather poor taste imo as helpful as the person is trying to be. But again, I also think the ad itself is in poor taste.