While I may be off track, I really feel sorry for this guy you love. I know that many people, when mortified, just want to go invisible; the reality of the situation is overwhelming. Now factor in that he's autistic. How mortifying to meltdown in front of someone who really matters to you! Of course he wants to disappear.
It is true that we need to accept and respect what people say. However, sometimes people trap themselves with words/decisions designed to self-protect, which is what it looks like to me. I find it promising that he contacted you again. That sounds like a concerned kindness, and a good start. And it's obvious that you care enough to see through to him.
Question: Do you think you can live with such behavior in the long term? Should he someday grow comfortable with you, it's still doubtful that he will abandon such behavior in general. Autism is not a hurdle the autist just jumps over, it's him. If you can look at that and still want to try, then it seems to me you ought to tell him exactly that. And it may be that he will take months to absorb and adjust to whatever he hears from you.
My NT wife loved me to her dying breath. What an unfathomable blessing to me that she was willing to work through the early uglies and the ongoing blizzard. Forty years. If it's true for you, then let this guy know that you loved him during and through that meltdown. It just may be exactly what he wants to hear, but fears it would be too good to be true. See if he'll let you prove it.