Self neglect

We're still struggling with issues around severe, chronic burnout, withdrawal and self isolation (mostly within just one room) in our adult son.  The thought occurs to me, especially given that this has led to very poor personal hygiene, absolute refusal (or inability) to engage with services or even, for much of the time, with family members, does this all at some point become more than self neglect and turn into more of a safeguarding issue for which we, as parents are responsible?  

If so, what on earth should we be doing for someone who has capacity but who uses this to refuse all help, especially understandable since his experiences with services have been entirely negative, even leading to a worsening of issues in the past?  We would hate to (once again!) enlist the help of any service which isn't autism friendly, approaches issues clumsily then leaves us in a worse position with well intentioned but ultimately useless suggestions like getting back in touch when he's willing to engage (this just isn't going to be happening any time soon) and comments such as, "We've never met anyone so unwilling to engage.  If only he would engage then ..." - i.e. simply echoing our difficulties back to us, withdrawing from the situation and leaving us without any support.  

This all feels very much like a stalemate situation but one in which we could be, while emotionally exhausted and trying to do our best, colluding with the neglect and thereby failing in our responsibilities and duties to our son.