Typically it is not a transfer they are looking for, but you can speed up the process.
They still do background checks, and testing, but for example training might be much much quicker.
Most departments like to get officers that are already trained if they can.
Places like Flower Mound and these cities don't hire that many officers though each year. Could be 1-2-3 a year, so it's best to apply many places due to the amount of competition and the vetting process.
He has to think about what kind of department he wants to be part of two. My guess is from going from NYPD to someplace like Flower Mound might be really boring. Most of the small cities around here for example don't like their officers running code in about 99% of the time. So if he is used to excitement and blowing and going all the time, he might want to look at the bigger cities like Dallas, Ft. Worth, Carrollton, Irving.
If he wants to ease into retirement, write traffic tickets, investigate petty crime, etc....FM or these other smaller cities might be a way to ease into it.....maybe provide some training to the younger guys, share the ways of the world with others who might not have seen big city crime.