Was it intentional? I really don't know. Only DeMarcus does. I suppose whether he did or didn't is in the eye of the beholder and how you personally feel about him.
It's akin to a controversial foul call at the end of a game. Fans of the player or team that received the benefit of said call typically believe it to be a good call while those on the other end of the spectrum believe it was wrong. Same logic applies here. If you root for the Blazers or have issues with DeMarcus, you likely believe it was done purposely.
Having said that, I can't really argue against either side. I can understand why many would feel it was done purposely. Even DeMarcus said the same thing after he saw a replay.
We can speculate until the cows come home but nobody truly knows but DeMarcus. All we can agree upon is that his mouthpiece did come out.
Either way, I don't care. All I do care about is Boogie's monster game resulted in a W for the team. Case closed for me.