This is bull****. Ducan said this as well.
You know what and I hate to tell you this, but I am not in "Transformers". I am so mad that I have to tell you that, but something happened and we didn't get the deal done and I was really hurt about that, because my friend Michael Bay is directing and he's like to me, one of the top action directors ever. I love working on his movies''
The real reason he did is not in Transformers is because Bay and Ducan couldn't work it out, not because Ducan thought the movie was crap. They are still friends, Ducan loves working with him. End of story.