Saw a documentary recently by a couple of guys that have had a lot of experience with grizzles. One of them a lot more experience than he wanted. Lots of bad scars and he lost an eye by an attacking Grizz. Both were carrying bear spray in the video and NOT in a pocket or back pack. Right in front of their chest in a holster that would be fast to access.
One of them mentioned that if he is in an area of thick brush he even takes the safety off the spray and carries it in his hand. I would think they would be as ready as you can be. I would not make the mistake of carrying my spray anywhere that I would have to fumble for a few seconds to get it ready.