The fact that you brag about it so boastfully is atrocious to be honest.
I didn't find his post to be bragging 'boastfully' at all. It reads chiefly informative and at times positively surprised. He found a technique that seems to work pretty well and he informs us about it.
I think your opinion is too harsh. Imagine yourself to be the customer of this website. You come across something you like so much you're willing to pay for it and you make the commitment to actually do so. Sure the revelation that the product does not exist yet is disappointing, but he also didn't take your money yet, and his website already convinced you that the product is going to be what you're looking for.
The shady part is doing the pivot without doing another opt-in. It's a classic bait ("Subscribe to get access to videos") and switch ("Continue paying to get access to a community and the promise of plans to make said videos in the future").
There's a major difference between trying to scam someone and pushing the boundaries to validate (and de-risk) an idea. If our ideas are shit, I will never take someone's money for that (hence the no questions asked, full refund).
These are Hacker News commenters, prototypal white knights eager to show off their perfect moral compasses, disregarding any opportunity for reflection or relativism.
No, it is not something I would have done, but I really understand the need to have some idea of what's going to work, and could see how one might go too far in pursuit of that.