my brother has always been rather weak in being able to speak out and stand up for himself, especially when it comes to taking care of himself personally Sounds like my 18 yr older brother. He was too shy to buy ice cream when he was in elementary school. Our brazen oldest sister did it for him.
My brother died in 1986 because he let his medical care go by the wayside. When he finally went to the Dr, it was too late. He lived 6 months.
My step-father created lots of conflict and I learned to be more assertive than my brother. My brother was M when my step-father showed up.
Moving 28 times between 2nd. and 10th. grade and going to different school forced me out of my shyness.
I didn't like my step-father, but have to say, sometimes I needed to stand up to others and I did stand up to him sometimes.
He has no problem if he thinks he has been wronged, i.e. like his wrongful dismissal suit he has going. That is a start, a seed to be developed and branched out so it covers/extends to less serious issues and to his personal life.
Shy or what ever some people call it, I tend to get what I call "stuck," related to procrastination, at some place and have a slow time getting un-stuck. Don't know if your brother is similar. Just thought it might help so passed along the idea of getting "un-stuck" might be more helpful than some other line of thinking.
Hope your brother is making progress. Best wishes to you, Mr HW, and your brother.