What was Michael's theory about how Sebastian had entered the Games in Virtually True by Paul Stewart?

According to Michael, Sebastian was probably playing those games when he banged his head in the accident. The computer had saved all his memory onto its own. when Shultz's family was in hospital, a lot games were stoled and ended in a computer fair where it was bought by Michale. When Michael was playing those games, the computer was trying to retrieve Sebastian's memory. So by this incident Sebastian entered the game in the virtual world