Framing a flywheel as a "simulation of a turbine" is really bizarre, unless there's something quite weird about this particular flywheel that the article fails to make clear.
It is to mimic the spinning turbine generators, which themselves act as flywheels, but in this case without the turbine part. The rotational inertia gives stability in that the frequency cannot suddenly change. I thought that was quite clear from the article?
The article isn't unclear, it's just weird. Smoothing out the input power is doubtlessly the most common purpose of a flywheel, second to power storage, and both of those is what this flywheel is for too. Describing a flywheel in terms of a turbine due to turbines acting as flywheels is the part that's weird.
As somebody without the domain knowledge, I thought the article did a great job of making it clear what the flywheel is doing (though of course it could be misleading in some way and I wouldn't know). I'm honestly a little confused as to the nature of your objection about which object is described in the context of the other.
I'm not 'objecting' to anything and I don't think it's misleading. I just think it's weird to describe a simple machine in terms of a more complex machine by pointing out that in one aspect the more complex machine is doing what the simpler machine does.
It's like describing a light-switch in terms of relays. Not wrong, not even misleading, but normally you'd expect the comparison to be made the other way around; describing relays in terms of light-switches or the rotational inertia of turbines in terms of flywheels.