By the time those forces had forgotten the threat he and Bella posed, Zhou Tian knew it would take a long time, and he wasn't prepared to lurk in peace. Thus, if he was unwilling to wait, he would simply have to resort to unexpected tactics at that time.
Letting those forces forget him was indeed the safest method of handling the situation. However, if he couldn't wait that long, it wasn't that there were no other methods to consider. For example, Zhou Tian thought of a way to attract their attention to solve the current difficulties.
The reason those forces were so fixated on Zhou Tian wasn't that they held significant grudges against him. Frankly speaking, Zhou Tian hadn't done anything too outrageous, the real reason those forces were fixated on him was that they felt threatened by his alliance with Bella. Had it not been for that reason, those forces probably wouldn't bother with Zhou Tian at all.
