Miss Beautiful Demon Fox Chu Qing's goal was quite clear: she wanted the Daluo Heavenly Tribulation Heart Sutra, and if the Golden Cicada could not cultivate it, and the Plague Source was also of no use, then there was no harm in Shen Qiang selling or even giving it to her, since she found him somewhat pleasing to the eye.
But the current situation was that both the Golden Cicada and the Plague Source were cultivating the Daluo Heavenly Tribulation Heart Sutra. If Beautiful Demon Fox was not one of Shen Qiang's people, then one day in the future, it was very likely there would be a conflict involving Beautiful Demon Fox Chu Qing using the same Heart Sutra.
Not only this, but there was also a high possibility that once the Daluo Heavenly Tribulation Heart Sutra fell into the hands of Beautiful Demon Fox Chu Qing, other demons could obtain it.
This was a scenario Shen Qiang absolutely would not allow to happen.