Han Sen had gauged the power possessed by Manager Qu and his followers. They were not far from the strength of a super creature, but the strength they had was not stable. It wasn't pure.
When they became blood-horn shura, their abilities were akin to that of a celestial being. They could unleash elemental projectiles, yes, but they were not even able to defeat Han Sen, whose fitness was around two hundred and sixty. Their purity and stability were too low, which led to their inability to compete.
Another thing was their lack of experience with the powers that had been bestowed upon them. Whether it was because of a lack of practice with such strength, or the inability of the power to be wielded with finesse due to the fact that it came from medicine, Han Sen was unsure.
