IMO, Di Resta move was more blocking and pushing Senna off the track, it was more obvious than the move between vettel and alonso at Curva Grande.
But it wasn't a surprise that the stewards are inconsistently handing out penalties.
Looks at the reasoning they used to ban Grosjean.
"It eliminated leading championship contenders from the race."
This is a very risky reasoning to hand penalties to drivers.
Sometimes I don't see placing an experienced driver in the stewards panel can help.
Also, if its wrong, at least its consistently wrong. That'll be better.