I think he's saying that the rule of public good (low pay) applies to non-profit workers, it can easily be applied to teachers. With the implication (again, I think) that it's not fair to expect public school teachers to take a vow of poverty and so it's not fair to expect the same of non-profit workers.
That pretty much sums it up / restates it / clarifies it / etc.
All organizations are competing for employees. If you believe in the cause, or the benefits (you like the AMC, you like working with children, you like having summers off) then you may be willing to accept lower pay, but it does not follow that it is expected you should accept it.
Tim