The way I see it, Manny has 2 big issues- Depression and maturity. They intertwine, but also work independently.
In order for him to help his depression, he'll need to mature as a person. Sometimes this takes a little tough love. I think Saban and Mueller called around judging interest in a trade knowing full well that a kid with maturity issues who cannot practice while on Depression medication would not attract a bite from anyone, and it didn't. And I think letting the media run with the story was Nick's way of saying "I can let you go elsewhere, but nobody's going to want you like this".
I beleive Nick wants Manny to succeed, not just on the football field but in life, but knows he must toughen up as a person in order to battle his demons. This is why he just hasn't flat-out released him yet.