That's not the assumption at all. The percent of cheaters in online chess is approaching an asymptotic 0 (as a percent of all players) simply because the sites, and chess.com in particular, have gotten very good at culling them.
But things like this are social. I didn't follow this (or even know it was going on somehow) but it seems very safe to assume that somebody and probably multiple somebodies were regularly pointing out and discussing engine moves.
So my only real assumption is that a significant chunk of people would end up deferring to the engine moves rather than their own preference. Of course my implied assumption there is also that a significant chunk of people were involved in the social aspects of this, but I think that's also a fairly reasonable assumption.
Based on a quick skim of the article, I don't think this was, for example, Twitch Chat picking moves, which might enable the social aspect you're referring to - although I'd like to point out the difficulty inherent to being in a room with many thousands of people, all spamming chess moves, and trying to find the one engine move :P
It's not that. It's that once you know the best move you start to see why. And then it becomes hard to get it out of your mind. It's the reason I don't recommend computer assisted game analysis, unless you just want a quick blunder check.
A very non-zero chunk of people also probably would not have even understood that that's cheating if it wasn't really clearly laid out in the interface somewhere. For instance computer assistance in the largest correspondence chess league is legal.
There are writeups about this. The sites score each move, it is extremely unlikely to pick superhuman moves multiple times in a row. Once or twice maybe, but not most of the times.
They do a lot more than just that, but a lot of the process is kept confidential. There's a huge cat and mouse game between cheaters and the sites so they try all sorts of things including only using second tier moves, and even 'blundering' but only in winning positions such that the blunder doesn't risk the outcome of the game. Some cheaters also only use the bot in certain parts of the game. In the extreme case you might have very strong players who are cheating (like in a money event) using only the comp eval. So they don't have an easy job at all.
Here, for example, is one of the more well known and easy meta-indicators of cheating: Humans spend more time on difficult moves than on trivial ones. Cheaters will typically spend a comparable amount of time on a trivial forced move, and the start of an exceptionally deep combination. And an even bigger tell is that said exceptionally deep combo may be followed by a couple of forced moves, yet he will again take just about the same amount of time to play those moves.
But things like this are social. I didn't follow this (or even know it was going on somehow) but it seems very safe to assume that somebody and probably multiple somebodies were regularly pointing out and discussing engine moves.
So my only real assumption is that a significant chunk of people would end up deferring to the engine moves rather than their own preference. Of course my implied assumption there is also that a significant chunk of people were involved in the social aspects of this, but I think that's also a fairly reasonable assumption.