Are you getting all this from the Canadian "Season 4"?
Because that's not Airwolf canon.

I remember that I have seen this episode about 30 years ago. I only saw it once and I always wanted to see it again. Now I have the complete series on DVD and I can't get myself to see it. It's not right.
I loved JM Vincent and I totally fell in love with Stringfellow again. He is the only hero of my childhood who was able to stay cool.
I personally think that String has died. I remember Saint John saying that he has a brother watching him from far away. I think he meant String is watching him from heaven. Because if String was still alive, do you think Saint John were able to keep him away from the cabin???
And I found that I like even less was that Saint John was alive and free all the time, kept in a super secret mission. I mean poor String is risking his life to find him and then you got to learn that he was there all the time and didn't tell his little brother????
THAT really sucked, even when I was young.