DD, I think your friend is exaggerating somewhat, or at least not giving you a full answer.
Yes, grizzly bears are extremely quick. If you walk up on one protecting a carcass, the charge will come from inside 25 yards and will be so fast your head will spin (right before he bites it off...). But many encounters occur at that range that don't involve an immediate charge, and you'll have time to unlimber your slug gun or unholster your sidearm. I have unslung my shotgun more than a few times when bears were in the 25-50 yard range, and once inside of 25. Handguns can be deployed equally fast, as can bear spray.
The key is knowledge of bear behavior and habitat, and keeping your eyes and ears open.
I know of one Montana ranger who drew his .357 Magnum while the bear was on top of him, and managed to kill the bear. Range between you and the bear is not the primary consideration when you have to act to deter/abort a bear attack.
