It’s contextual.
You shouldn’t remain indifferent to repeated unfair treatment or disrespect. If it’s a random person or someone you won’t see again, sure, brush it off. But when it involves people who you have frequent interactions with (co-workers, friends, family, LTRs), you’re better off caring enough to confront others if their behaviour towards you is not to a standard of respect you’ll tolerate. This doesn’t mean react emotionally or reciprocate the disrespect, it just means be assertive and stand up for yourself when necessary.
I agree for most situations indifference can be useful, as it can pay off not to invest so much mentally on such trivial things (especially women flaking)...
But I’d argue that emotional intelligence is an even more powerful instrument a man can utilize in his dealings with women and life. It can be applied universally with no downside, it is beneficial in every context.