If you are between your man and the ball you can deny AND help. It's kind of a funny thing, also the defensive philosophy for Mike Krzyewski, Bob Knight, Lon Krueger...
Haven't you ever been playing a pick-up game and identified who is going to help and who needs to stick with their guy? Haluska is usually the one who needs to stick with his guy.
Furthermore, I have a tough time believing that you have watched Haluska on an island enough to even make a educated judgment on his help defense vs his on the ball defense.