Agoraphobia can manifest itself differently in anyone who suffers from it. Bob may be able to leave his house, as long as he doesn't go more than 5 miles from it. Sarah, on the other hand, might not be able to take 1 step out of her house, or even open a door or window without anxiety. And then this friend of yours just has where they cannot leave the house for more than a specific amount of time, 24 hours. Just because it doesn't sound like someone else's agoraphobia experience, doesn't mean it cannot be agoraphobia.