I laughed when I read that....agreeing that it just shows sarcastically Isabella's character and attitude with men, which is a bit on the self-serving side and attention-seeking as mentioned. It's funny Isabella sees the way to "humble" men as making herself and Catherine the object of their attention.

Catherine is all out to be discreet and Isabella is all out to risk not being so.

Chapter 6--on the way to Edgar's Buildings

Catherine readily agreed. “Only,” she added, “perhaps we may overtake the two young men.”

“Oh! Never mind that. If we make haste, we shall pass by them presently, and I am dying to show you my hat.”

“But if we only wait a few minutes, there will be no danger of our seeing them at all.”

“I shall not pay them any such compliment, I assure you. I have no notion of treating men with such respect. That is the way to spoil them.”

Catherine had nothing to oppose against such reasoning; and therefore, to show the independence of Miss Thorpe, and her resolution of humbling the sex, they set off immediately as fast as they could walk, in pursuit of the two young men."