Probably just common practice for our area. It is done all the time. When I bought my first house in 1987 it was a FHA loan. They were requiring painting on the garage and the back of the house. We paid $100 to get the second floor of the back of the house done as our Sellers wouldn't do a thing. We paid it and we painted the garage. Then we closed.
We were approved- this was a last condition to get to the closing table. So wouldn't you paint it if it was a condition of the loan and your Seller wouldn't- or couldn't do it?
To me- it was a matter of losing the deposit, fees to the Bank and not having a home.