Tobias was supposed to be come some hard kind of guy as opposed to the bully magnet he was. People die all the time, and although some people, like Marco's dad, take it really hard, other people manage to overcome it either through their friends or through their own strength. I don't feel the rest of the animorphs had a good opportunity to help him, just proving he was still the same old bully magnet without his singular source of strength.