When dudes say they are focusing on improving themselves, getting money, etc. they are basically saying they aren't feeling the chicks they can get in their current state, and are just gonna wait to see what they can pull after this period of self improvement.
It's a misnomer, because they technically do have the time to get casual sex and have it not interfere with their hustle, but the amount of effort that may need to be exerted to get what they really want may be more than what they feel like doing.
I understand what they really are saying versus the technicality of the words. My only objection is that regardless of your focus, you should continue to interact with the opposite sex, regardless if it's a sexual situation or not. You don't want to accomplish your goals and then when it's to put in work you don't know how to interact with women.