Is he an exercise physiologist or a kinesiologist? If so he should go back to school. One head of the biceps crosses the shoulder joint so you use it more than you think.
3 things come to mind.
1) Shooting(lower hand in particular)
2) Lifting the stick of opposing players especially if he doesn't want his stick lifted. A lot of bicep there.
3) Faceoffs and especially reverse grip when your pulling it back.
Biceps are a big muscle and should be trained like anything else. I think someone on here just tore one playing hockey. How do you tear it if you aren't using it?
I've read in a few places that hockey players should avoid adding excess muscle mass in your upper body -- the added weight will slow you down. That's not to say that a player should ignore their upper body. Just know what muscles you're working on and how they will improve your game.
Anyway, with regard to hockey biceps are just window dressing. Working them will probably allow you to scratch your nose a bit quicker but that's about it. They provide such a limited range of motion, but guys will tend to isolate and build their biceps because they make him stronger. If you want to add power to:
1. Your shot -- work your core abdominals, especially with a rotation move like the woodchop. Work your legs (quads, glutes, hammies) with lunges. This is where most of your power comes from. Your triceps (your lower hand) driving your stick blade forward, the snap of your wrist and even the bend of your stick probably contribute more to your shot than either bicep muscle -- that's only used if you pull your top hand back as your lower hand goes forward.
2. Lifting an opponent's stick -- quickness and the element of surprise are far more effective in stealing the puck. But if you're mucking along the boards, again you'll be better served with strong legs and core muscles for stability. Shoulders and back, too.
3. Faceoffs -- First, unless you're a center this is irrelevant. But if you are taking faceoffs regularly then being able to pull back with power is a definite advantage. And unless you've got a solid base (legs and core) to anchor you a strong pair of biceps is useless.
As for the torn bicep you mentioned? I didn't see the thread you're talking about but if the guy in question used only his bicep to lift something heavy (opponent's stick, hockey bag etc.) without engaging his legs, core and back then it's no wonder he tore it. Major muscle groups should take the brunt of any weight, while the smaller muscles should be used primarily for providing stability. Using a small muscle like the bicep for a big load will only lead to injury.
