could have just been a simple No, I don't feel comfortable doing that and not a lecture to Mark (and the club).
Mark could also have approached me through a PM instead of doing a public off-topic post to a classifieds listing. He would have gotten the same opinionated reply, but not in public. As a matter of fact, you could have sent me a PM, but you decided to also make a public post of your opinion. So, I'm also replying to you in public.
I remember the early days of the internet, when all the nerds had bright visions of information being "free" and it leading to a type of unfettered utopia. Instead, we have constant scams, conspiracy theories, and disinformation campaigns. It has lead to genocides (such as Myanmar) and wars (as in Ukraine). The internet has become a means for countries to destabilize their enemies, by pitting citizens against each other with social media memes and fake news sites. People will repeat anything they see as if it was truth, just because it was "published" on the internet or because they've "heard" it more than once. Back in the 1990s, the nerds had no idea that some things shouldn't be on the internet and that reputable gate keepers were a necessary protection against human nature.
Nope, I'm keeping my aircraft off the internet as much as possible. The local gossips are bad enough. These are not vintage cars. Pedigree is much more important with airplanes and maintaining your own public database of them is a dumb idea. One guy decides he thinks a certain aircraft has a hidden corrosion problem because he heard it from a friend and that can become a "truth" out there (an example that I've witnessed, when a potential buyer wanted to ruin the market for an airplane so he could get a better deal for himself). A lie (or a mistake) is really hard to fight once it has gotten a public airing and I don't think they should be given another breeding area. I will send DMCA notices if I find on my aircraft in any such database that wants to represent its condition through images or description. The FAA registry should be the only source of information on US registered aircraft.