I understand as much as I can, regarding your sitch with SS21. And I am happy that he is at least in a day program where he has good care. One of the things we have around here is respite, which is a pocket of money which allows for support so that the parents can have a break from time to time.
There's an amazing quote from a man labeled with learning disabilities. He said to his workers at an institution: "Is it that I cannot learn, or that you cannot teach?" It is the belief of many and that understanding is growing, that everyone is entitled to and capable of independent living. The question is, was your SS21 dismissed because he could not be supported, or because they did not know how to deal with his outbursts? I mean, common... you guys haven't kicked him out of the house and sent him to an institution...
OTOH, regarding your W. I accept your defense of your W with respect to your SS21. I can appreciate where she is regarding trying to figure out how to care for herself right now, never mind the support (parental love) he needs and desires. Like any child who's parent(s) might "check out", they will feel the loss and will act out. I also applaud your stepping up to fill in the support during this time, as well as before.
I need to stress (and question) is his behaviour the same as it always has been? Or are you seeing a difference recently. And understand that behavioural changes with people who have autism is as normal as behavioural changes with people who do not have autism.
I'm sorry to push this, and while I would not consider myself anywhere near an expert, this has been a part of my life for pretty much as long as I remember, as I've said before. There is not a single case where an individual with an intellectual label cannot be supported appropriately outside the family home and outside an institution. Some parents and "professionals" sometimes just need to look a little further and a little deeper to see the value and opportunity. And then... like your W (and you to a certain extent)... the parents need to step up and step back and allow their children to move forward with their lives. Tough in a normal situation, sometimes moreso in the case of special needs, because of the overwhelming care requirements as the children are growing up in the times we have lived in, with respect to how we understand special needs.
If you wish me to stop talking about this, please let me know. I will honour that. I am just trying to help you (and eventually your wife) that there ARE solutions and support options for your SS21, even if they currently do not exist in PA or your specific area. IIRC, PA has a decent program and they are making great strides forward.
In the mean time, a disrupted program (or as some may say, change in "routine") will affect anyone, and especially affects people who have autism. The outbursts and changes in behaviour may be related to your wife "checking out" or they could just be changes within the individual as an indicator that they are attempting to grow and become more independent or are looking for stimulation elsewhere.
Your W may never want to accept that your SS21 can receive "proper support" elsewhere, especially considering past track records. But with new information and resources and a team (we create "support networks" here) who is willing to help your SS21, he can have the supports he needs and reduce the pressures of the parents and family. And it is NOT a criticism of her parenting. Her response is "normal" and is witnessed on a fairly regular basis. It's whether she is open (how she receives the information, perhaps) to the new ideas of support.
Your SS21 needs a support network to move forward with his life... and your W (and you) needs that as well... Look into that and you may find exactly what he needs and is looking for. The support network is filled with people who range from those who can directly support him, as well as friends, family, and professionals... These people exist, so do programs that can help develop this for your SS21.