Reddit reviews Defensive Tactics: Modern Arrest & Control Techniques for Today's Police Warrior

That's true. However, it's sort of like saying that Marines don't need hand-to-hand training because they have M16A4s. It's true, they will not necessarily WANT to use hand-to-hand and they will most likely not need it, but it's there if they do happen to need it.

Krav Maga is a good place for combined approach, as their training regime should (at least, in proper krav maga) include weapon and empty hand techniques.

http://www.amazon.com/Defensive-Tactics-Control-Techniques-Warrior/dp/1880336995

This is intended for police, but it includes weapon retention, empty hand techniques, and baton use and is well written.