Putting aside your semantics about you thinking you are not blaming March (the others have addressed that), I think I see where your premise is falling over.
I know one family where one son has rocked on, the other is a $&@# up. Both raised the same, taught the same, and lived under the same conditions. Difference is one listened and learned, one didn't.
You seem to be assuming because Martin is skill learning "life skills", he hasn't been taught. Ever thought he has, but he simply hasn't applied what he has been told? Left school at 15, casual jobs, and then life in footy - hardly the background of a guy who seeks stability and security.
As I've said several times now, sooner or later Dusty has to take responsibility, and to his credit it sounds like he has.
March deserves praise for taking him into his home, and treating him like family. Most wouldn't have even done that