Careful now, I suspect the author did know about this site and looking for leaked demos, or that we have a white knight here for the lack of leaked demos
White Knight or not, the demos started dropping or being locked away after Dashingdon went down because somebody shared links of this site on the Hosted Games subreddit and COG's forum for people who wanted to know where to read their old favourite demos, and a majority of people found out that there was a pirating site for the games and went wild. That's when everything started to become too mainstream for the authors to ignore and the host of cogdemos decided to create a pateron lock on their site.
But before that if you searched up a finished game, Dan's mods would always pop up in google anyway. Years ago I thought that this was just some sort of forum mocking COG and never looked at it because it looked super basic at the time as I suspect many others believed. Now the site is renown, better looking and most of the COG fanbase knows about it. So, unless the site went on lockdown, it was always going to be found out.
The death of Dashingdon was just the final nail in the coffin and alerted the entire platform about this place, and most of them can't shut up to save their lives.