When Ainsworth finished reading the contents of the S-grade side mission, he knew that Rian and Dante would agree with him in accepting the side mission.
If it were only the side mission's objective, the three of them would be resistant to doing it. After all, no one wanted to lose their humanity and become a zombie.
Fortunately, there was an alternative objective that could be fulfilled by letting a controlled zombie complete the side mission's objective for them.
It just so happened that there was already a controlled zombie that Ainsworth had, which was Kyle.
Coincidence? Most certainly not.
If any of their teammates became a zombie, whether intentional or by accident, then they would undoubtedly trigger this side mission.
However, the act of controlling a zombie met the conditions for the alternative objective which in turn, triggered the Road To Zombie King (S) side mission.
