Its definitely a MM and it will propably not have another molt, they can have a post mature molt but usually don't survive from it.
Grammostola Mature Males can live for up to 3 years after maturity, saying that it only has a couple of months left might be incorrect, If we know when the guy has matured will give a better indication of how long he still has left. But saying that he can't climb glass anymore gives a good indication that he has probably been mature for quite some time now.
My advice would be to remove the coconut hide, I don't think he'll use it. Has he ever used it?
Provide him with a waterbowl that you clean and put fresh water in every couple of days and also offer him a food item every week or 2. If he does not eat it in a day or 2 just remove it.
If you do this, this guy might still give you a good years service or so
Or you can even find a female and breed them then you can have slings with his bloodline in them :thumbsup: