Yes it was. An awful decision for which Collingwood apologised. What are you expecting English fans to say that there was nothing wrong with that incident?
Grow up.
The other thing about that situation was that it didn't come at a stoppage in the game. With this decision it was possible for Adrenaline to die down and Dhoni could come to a proper decision. Had Collingwood been given that time, he may have done the same but this was mid-match.
Had that happened in the middle of a session, I dont believe there is anyway Dhoni would have overturned the decision.
Massive respect to Dhoni, but as I say, had it been mid-session the decision wouldn't have been reversed.