Some might say dowling on the race line significantly and grossly slower than is reasonable knowing a faster rider is approaching is reckless. It would certainly be reasonably to do what lap riders do all the time, be aware of one's surroundings, and in the interest of safety, move out of the way.
The thing is if the roles were reversed we could surely count on the slower rider being chastised for being flagrantly dangerously slow around Rossi. I'm sure if Marc had been close to 4 seconds slower than potential, and Rossi took the inside to pass and an incident ensued, I could already hear journalists and fans smugly lambasting Marc for getting in Rossi's way. This would be so predictable. As Michael Scott correctly points out, Rossi comes out smelling like roses even when he's the villain.
As I said in another post in reference to Espargaro making a point about available flags, a blue flag waved at dangerously slow Rossi at Argentina would have been appropriate. And I'll add, the arbitrary penalty RD issued for his contact with Espargaro, something normally not punished, was compounded by issuing a drop position penalty instead of 'safer' option of imposing a....oh how did David Emmett put it? Oh yeah, "time correction". But then again, it's not like RD have a stellar record on issuing penalties that are corresponding to the current situation on the track.
If you live in a glass house don't throw rocks.