Some people only date traditionally, which is to say that they only pursue serious relationships with the ultimate end goal of marriage. If they can't date due to life being busy, they would just put their dating life on hold (and not have hookups with random people off apps).

Many men like this prefer seeking women who are traditional-minded as well, as in they date with the intention of a relationship (no casual dating or hooking up). It would make sense not to pursue women who are currently promiscuous or used to be promiscuous and then decided they're tired of that and want to settle down now.

No one should be able to oppose or challenge this mindset coming from a guy because he himself held those standards for himself.

There has been a lot of stigma around this where a lot of people would argue and say "but if you like each other, then it shouldn't matter if she slept with many other men before you". To this, if the guy is okay with dating a woman who was like that, then that's his choice. But if he chooses to reject her mainly because of her promiscuous past (or current nature), that's totally fine too. As long as he's not calling her explicit insults of course.

Contrary to popular belief, there are still many women who date seriously and only seriously, no hookups or ONS in between. It may be ideal for the traditional man to pursue women like this and weed out the rest. That's what dating is about.