Yeah but Time Stop wouldn't really have helped there with the context. His goal was to get Enri and Nemu away from the knights, opening with Grasp Heart because even if it's resisted, it stuns the opponent which would let him grab them and run. As you know, Time Stop doesn't allow Ainz to affect people time stopped, and he has to time his spells to trigger the instant Time Stop ends. So if he used Time Stop + Grasp Heart, he'd achieve the same exact result as he did just using Grasp Heart, either killing or stunning the knight, as it's not like he could grab Enri and Nemu while they were time stopped. Basically in that specific instance, Time Stop would not have meaningfully helped the specific goal he had in mind.
Hopefully I worded that well enough lmao