Diary of the Dead

The film begins with footage from a news cameraman and reporter, who are covering a story about an immigrant man killing his wife and son before committing suicide. The son and wife turn into zombies and kill several medical personnel and police officers but leave one medic and a reporter bitten before being killed. The narrator, Debra, explains that most of the footage, which was recorded by the cameraman, was never broadcast.
A group of young film studies students from the University of Pittsburgh are in the woods making a horror film along with their faculty adviser, Andrew Maxwell, when they hear news of an apparent mass-rioting and mass murder. Two of the students, Ridley and Francine, decide to leave the group, while the project director Jason goes to visit his girlfriend Debra (the narrator). When she cannot contact her family, they travel to Debra's parent's house in Scranton, Pennsylvania. En route Mary runs over a reanimated highway patrolman and three other zombies. The group stops and Mary attempts to kill herself. Her friends take her to a hospital, where they find the dead becoming zombies, and thereafter fight to survive while traveling to Debra's parents. Mary becomes a zombie and is slain by Maxwell. Later Gordo is bitten by a zombie and soon afterward dies from it. His girlfriend Tracy begs the others not to shoot him immediately but later is forced to shoot him herself. Soon they are stranded when their vehicle's fuel line breaks. They are attacked by zombies while Tracy repairs the vehicle with the assistance of a deaf Amish man named Samuel. Before escaping, Samuel is bitten and kills himself and his attacker with a scythe.
Passing a city they are stopped by an armed group of survivors, the leader being a member of the National Guard. There, Debra receives a message from her younger brother, who informs her that he and their parents were camping in West Virginia at the time of the initial attacks and are now on their way home. The students then leave for Debra's house. Their only reliable source of information is now the Internet, aided by bloggers. When they arrive at Debra's house, they find her reanimated mother and brother feeding on her father. They escape from the house and are stopped by different National Guardsmen, who rob them, leaving them only their weapons and their two cameras. They arrive at Ridley's mansion, where Ridley explains that his parents, the staff, and Francine were killed and he buried them out back. Ridley then shows Debra and Tony that he "buried" his parents, the staff and Francine by dumping their bodies into his family's swimming pool. Ridley then abandons Debra and Tony and is revealed to have been bitten by a zombie himself, explaining his odd behavior. Ridley soon dies, comes back as a zombie, kills Eliot, and attacks Tracy and Jason. Jason is able to distract Ridley long enough for Tracy to escape. Tracy then leaves the group in the group's RV. The remaining survivors then hide in an enclosed shelter within the house, with the exception of Jason, who left the group to continue filming. He is then attacked and infected by Ridley. Maxwell kills Ridley with an antique sword and Debra kills Jason, and continues filming. However, a large number of zombies begin to attack the mansion, forcing the survivors to take shelter in the mansion's panic room.
At the end of the film, Debra watches Jason's recording of a hunting party shooting people who were left to die and be reanimated as shooting targets, and wonders if the human race is worth saving.

Question: Why was Jason not hide with the others in the enclosed shelter within the house?
Answer: He left the group to continue filming