They are opportunistic, solitarty hunters. They do not "plan" any hunt. They will kill any potential prey they come across instead. Pack hunters, such as lions, chimps, dolphins, whales, and wolves, do plan their attacks. They wait until the best time to launch their hunt, and they coordinate with each other when hunting. Some members of a pack may flush a prey animal towards other members waiting to pounce for example. Such strategy does not work for solitary hunters.
Grizzlies need to fatten up for winter, so they don't waste time planning attacks. They simply eat whatever they come across, whether it is carrion, garbage or plants. If they meet humans, they have to figure out whether it is dangerous to hunt us. If they think it is dangerous, then they will go in another direction. If they are desperately hungry then they may ignore any possible danger we may pose because the danger of starvation may outweigh the danger a prey animal may pose.