Ehsan Kiani Oct 22, 2018:

Makes sense I think it totally makes sense. This is actually a sarcastic answer to the self-posed (also sarcastic) question before it. The parent simply didn't want the boy to waste time on his music and become dependent on them as a grown-up.

B D Finch Oct 22, 2018:

Very muddled Who is doing the throwing. The parent can't very well throw their son back on their own hands. Do they mean that they are likely to have the son thrown back on their hands by someone else? perhaps by the education system? Or is this about someone else's son? "if I had a boy of 21?" Is this a person with limited English giving advice to somebody else about that person's son?

Sheila Wilson Oct 22, 2018:

Muddled idiom, IMO It actually doesn't make any sense to me as it is. I think the writer has confused two or more idioms here.
Take/have someone back (in) - to accept someone back after they have left a relationship, job etc or let kids live back at home after they've been independent for a while.
Have someone on one's hands - to have someone that one is responsible for or burdened with.
Throw someone to the wolves/dogs - to place or leave a person in a bad situation.
Throw someone on the heap - to place or leave a person in a no-hope situation, regarded as a failure (heap being the scrap-heap).