I think you're somewhat mischaracterizing Gutierrez's intentions here. Firstly, it's become evident the team had not done enough research into Miller before drafting him. Their knowledge at the time of that first statement consisted on realizing he had a history of bullying, which they acknowledged as a negative, but yet still were of the belief that they could be part of remedying. Upon digging a fair bit deeper, probably further spurred on by the media backlash, it became quite evident that Miller's situation was in far more of a hole than initially thought, and that he'd made no real strides towards improvement, while quite possibly having mired himself in deeper.
At that point, it's fully reasonable for the Coyotes to realize he's too much of a project and he's not even close to making the NHL so how can they realistically even begin to work with him. He's not even taking the first real steps towards correcting any of this.
I still think an internal review on how this all went down is good, but I think you're ascribing too many nefariousness to Gutierrez when it's likely the team hadn't initially realized Miller is much closer to a lost cause than he is some one who just needs some mentorship.