SB, Hi, and I know it's so frustrating to deal with our difficult children and never hear from them what we so want to hear.
But...here is what I hear and see in your interchange. He wants to be with family. He's asking to meet with you guys to fish or grill out.
You have a choice here, SB---you can go and meet with him for a short time or not. Of course, don't let your younger son go alone---you would need to be there.
The question of whether or not you go comes down to this: Do you want to go, and what will it cost you, emotionally? Perhaps you can go and stay just for a few minutes---30 minutes or 45 minutes. Or shorter if things aren't going well. Or not.
You may remember that last time difficult child was homeless, I was seeing him for 10 minutes a week, and we were sitting in my car talking for those 10 minutes. It was actually pleasant.
One thing I would try not to do is continue to point out what he needs to do and how he needs to change. He knows that already. He knows what you think and what you want from him. Believe me, he has not forgotten.
But----He is doing what he is going to do, for now. Your pointing it out isn't going to change anything.
And in the back and forth texting, you quickly got sidetracked from the larger issue of his lifestyle and choices, to the text message sent that night. The circular argument started, and there is never a good resolution with the circular argument.
SB, instead, I would use "I" statements, and set boundaries, like you did.
"Sorry, we're already busy that day. Thanks for the invite."
"Your new boat sounds neat. (I know, I know, how in the world can he afford any kind of boat?)"
"Maybe we can get together and go fishing another time. Tomorrow won't work."
"Oh."
"Thanks for calling."
"That sounds interesting."
Then, if HE wants to push on WHY you can't ever meet with him or what is wrong or why can't I move in again---THEN you can tell him why. You can tell him again.
Until then, I'd try to keep it simple, keep it encouraging, keep it light, keep it cordial. Just like you would with anybody.
SB---here is what I see: He's working, he's not living in your house, and you're not giving him any money. He isn't in jail, and he's held down a job for six months. He has a place to live today.
On some level he is functioning. It's not the way you and I want him to function, but he is functioning.
This may be how it is for now. Or for a long, long time. Can you accept it? And what does acceptance look like?
A phone call a week, a text exchange a week, sitting in the car for 10 minutes once a week, going fishing one afternoon?
That is completely up to you and I would make that all about what I want, not what I think he needs.
Warm hugs. I know this is very very hard. We are here for you. Take what you like above, and please, leave the rest.