The zombies were evolving and Jason was aware that the dangers that waited for them outside the walls were worse than they had anticipated.
He could only pity those who encountered these zombies as the only reason he could survive was because of Chronos.
Chronos was the one thing that granted him the chance at survival and he could only imagine the damage that Sam might have done if Chronos chose him as the host instead of him.
Sam would have been a far better choice and the weight of the responsibility was beginning to weigh on his shoulder.
He was feeling the pressure of things and he couldn't believe that he managed to survive this long even though it wasn't on his own.
Jason was tired of being made a fool and Debra probably mistook him as someone who could be walked over, he wanted to give her the benefit of the doubt but something told him this was intentional.