Hopefully I don't upset too many people here, I'm honestly open to conversation. I research a lot of debates/conflicts, haven't touched the gender debate in a while, so we'll see how much I remember.
Ultimately, I think AI replacing women is a step down from healthy relationships in general. A healthy relationship is about both give and take, which is paramount to operating in groups, but the problem in the West is that third wave feminism aka (intersectional feminists) are a dominate force in Western Society, and that is anything but healthy. Proponents of sex bots usually fall into the MGTOW group.
(third wave summed up in six seconds by their own words)
https://www.youtube.com/watch?v=SA0aKjY8K50
Why is AI a step down? Well, first off a functional society values role based and traditional hierarchy, while not all hierarchies are equal they do require a two way give and take which teaches us about distribution of responsibility, cohesion, etc. Having an AI companion removes the give part which would hamper ones ability to learn such traits.
On the other hand, intersectional feminism seeks a one directional system of give and take. Particularly maintaining the old advantages under traditionalism without any of the costs. Comparing systems it would look like this.
Traditionalism- Social obligations / societal expectations precede rights. In that if you are outed and expected to serve a particular function, you need the right to enable you to serve that specific function, this is seen across cultures. So the system within traditionalism translates to Group 1 receives benefit A and the Cost of benefit B and Group 2 receives the benefit of Y at the cost of Z. (1:+A-B, 2:+Y-Z)
Traditionalism isn't the only system, you can advocate zero responsibility between the genders, which is what the MGTOW people advocate assuming I have not mistaken their position, thus they want to do away with the whole benefit/cost trade offs, which in my guess is what the OP registers as. Of course there is also intersectional feminism which also opposes traditionalism by advocating the equalization of benefit A, effectively removing it from the equation while some also focus on eliminating cost Z. (1:-B, 2:+Y(-Z))
So tying this in, I see sex/companion bots as a way of dealing with intersectionality, by avoiding it implemented by the people who compose of MGTOW. As oppose to traditionalist who challenge intersectional culture with their own, PUAs who simply use intersectional culture against itself, or male feminists who conform to intersectionality as a way of staying in the market.