I know the game wants you to think hes dead and the developers have 1 "true" ending that they have to build off of. What if Lee was just bleeding out and was weak and passed out from loss of blood? Its possible he could regain consciousness and find a way out. The loss of blood would make his character appear weak and pale just like the bite would. He was also never bit or w.e. he claims but the walker scratched him with his teeth. I think him not being dead is a possibility for season 2.