He knew that she had allowed him to acquire so much information about her without blocking because she didn't have a much lifespan to spare. So he could guess that if she were forced to lose too much lifespan because she was blocking an inquiry, she would become afraid of dying and choose to run away.
This was why he only let her lose 100 years of lifespan before backing off. As for the two new divine beings whom he didn't know anything about, he only made them spend 300 years of their lifespan blocking him.
On the other hand, he took 500 years' worth of lifespan from Forced Exchange with the inquires. He limited himself to this, not because he didn't have the lifespan to burn, or that he wasn't willing to burn the lifespan just to make his enemies lose more.
He had a long lifespan and was willing to burn his lifespan to make the four of them lose their lifespan. But he held back because he wanted to appear weak.
