Who wrote that? It sounds like a Trump supporter justifying when things don't go Trumps way. Rossi might prefer the latest version of tyre to the other choice but overall he has much less advantage than in the past which makes it even more impressive he won Assen.
I wouldn't deny that anyone invovled in the management of MotoGP would want Rossi to be there as long as possible but those arguments do not work for me. Rossi is so good on the brakes that the stiffer carcass works for him but otherwise he is broadly the same as Vinales in what he needs to make the Yamaha work.
The Michelin era has made the championship much less predicatable and way more interesting to watch. The satellite bikes all have a genuine chance to win if they have a good enough rider where as a couple years back you had to be Rossi/Marquez/Lorenzo or some other rider on a factory bike to stand any chance of winning more than the odd lucky race.
Rossi is riding as strong now as he ever did, but fortunately there is such good competition now that it's not enough to guarantee the win. Look at the lap times and points between the top riders, it doesn't get any better for the viewer. Plus Ducati is currently leading