Since Quinn had evolved, it was safe to say that with his Charm points, there wasn't a vampire or human that he couldn't put under his influence skill. The fact that he could easily control Yaddy, who was at the vampire lord level, proved this assumption.
However, while he was in slumber, the humans had all learned how to utilise Qi. It seemed like the second stage, to form Qi into shapes, externally and internally, was prioritised because of vampires.
It was made to counterattack the Influence Skill, which was why Quinn couldn't just use this on humans for information as much as he would have liked to. On top of that, he was trying to find information of what exactly had happened in the 1000 years, which wasn't something any random person on the road would know.