> Why? Twitter included lurkers in its dataset, this article didn't, why should that impact stats in the direction of fake accounts being smaller?

Because you usually don't create fake accounts to lurk, but to do "something".

I'm speculating, but even when you create bots to boost follower counts you'd probably make them post now and then so as to seem "active".

It makes sense that the proportion of tweeting accounts being bots is much higher than the proportion of lurkers. And since there are also more lurkers in turn than posters, I would say that the real number is much lower than that.