There's a difference between criticism and threats.

Even if one concedes that Obama is incorrect on the role of a superdelegate, I don't see how suggesting those delegates "think long and hard" about how to vote can be fairly viewed as an act of intimidation or retaliation.

At worst, Obama seems to be saying that failure to listen to their constitency may have political implications for them.

If, on the other hand, you can show that Obama is promising to use his influence to create political implications I could see what you mean. But from what you posted I don't see it.