I think by "low tier men," he means men that flat out are sexually unappealing to women and likely would have gotten passed over before we had monogamy. Men who not only are physically unappealing but have no charisma or social skills either.
Problem is, if things revert back to the way they were pre-monogamy, even average and slightly above average men are going to get shafted. I don't think anyone can say with a straight face that 90-95% of men in a society are "low tier". This is like saying that every car that isn't a Rolls Royce is junk.
Darwinism is a horrible thing to base civilization on.
In a highly materialistic leftist society, the way I see it is that woman, more so the top 20-25% or so attractive, are only typically impressed with a man who is in the top 1% or so of some category that interests them. It's one reason why the red-pill views of all women are jumping on chads and falling off is wrong. That's a minority of women.
Some women are really interested in intelligence, "confidence"/game, finances, charisma, social status etc. They seem to generally have a minimum common standard of looks, which should not be too difficult for men who work out ~7+ hours a week, dress presentably and keep themselves groomed. But then all these traits they have a minimum standard for stack up, e.g. they don't want someone who has the energy of living with mama, the above and others.
I've seen some women repulsed by better looking men whose charisma is off putting to them, women swoon for shabby intellectuals, and fairly good looking girls disinterested with 1% guys. Many women are shy and conservative. They might find a guy attractive, but an arrogant manner that suggests she should be into him physically from the off - off putting. I am the same, some times in my life women who I found physically attractive have came on strong to me, but I find flirting and anything beyond it disgusting. What kind of a woman sexualises a conversation from the off.
The man in the modern leftist society must meet as many women as possible, in the hopes that one will find something about him impressive enough to spark a relationship. But then there is no guarantee that woman will be anywhere near marriageable or interested in marriage.
Data shows only about 1/3 of males 18-24/5 in the US are in a relationship. A lot of that is guys who are near the 1% of something a woman thinks is impressive. As the years pan out more women accept lower and lower levels of impressive. We're probably about the stage when around 50% of men aged 30 have never been in a relationship.
Very different when you take the leftist out of a materialist society. Russia is far more materialist than America, at least in a sense of material gain*, but men are not weighed down by leftism and women are not held up. Men are almost universally expected to be competitive and perform. Feminism is near universally considered an embarrassment. Just the very nature of the men this society produces (more masculine) mean women are more interested in men, and they need them more for everything financial and social.
* Material complaint (leftism) is more materialist in essence IMO, but not as most people would consider, as the leftist mind is far more pre-occupied with social/material stakes than your average person who likes fine things