What indicators have you heard from him that makes you think he "realized this" as you said?
An empty "mommy bucket" is an interesting way of putting it... .that's likely his core pain. Identifying and validating this pain is likely to produce more fruit then telling him what to do from your point of view.
The main indicator was that he came to me and talked for a few hours about it--he saw how he was "influenced" by his mom, talked about how he realizes she doesn't always tell the truth, how she has inappropriate boundaries, how she has never been a "mom" figure, but acts more like a friend (and how she is still trying to regain her youth). He was saying that he thinks the main reason he wanted to live with her is that she has never been a big part of his life... .I definitely validated that.
I was shocked as I had never heard him say ANYTHING like this at all, and I asked him when his big "aha" moment was, and he said he had been piecing it together for years. He rarely talks about anything, much less what is going on in his head--he is a people-pleaser and wants everyone to be happy.