My son left 2 rehabs. He just graduated his third.
I was an active participant in my son's first 2 tries. I blamed myself for his problem and took it upon myself to do as much as I possibly could to help him fix it. Impact letters, visits, training, family sessions, whatever they said might help, I was there with bells on my shoes.
The third time I was done, done, done. I had no involvement other than visits and showing up for his graduation. If he was being a jerk he didn't even get the visit.
Rehab is hard and scary, and the rush of emotions when newly sober is overwhelming. I agree with Earth is Hard. Your son's counselors know what he's feeling, they have probably heard all of his excuses before, and they know the right things to say.
If *WE* knew the right things to say they probably wouldn't be in this situation. They need people who can see through their BS and have enough professional distance to let them decide what they want. If his counselors feel it is best for you to step back and let him figure this out on his own, I would defer to their judgment.