there are plenty of women who have XY chromosomes and have complete androgen insensitivity, like Alicia Weigel

Matt Walsh's anti-science "documentary" What is a Woman doesn't really engage with intersex individuals, but in his public speaking, Walsh insists there are no intersex individuals, because he has an idiosyncratic definition for intersex. Basically he believes you can only be intersex if you produce both gametes, he seems to believe you can classify all intersex individuals within the gender binary based on which gametes are produced and thus none of them are really intersex. As a source, you can see him summarize some of these beliefs in this video.

He's also wrong about there being nobody who has ever produced male and female gametes, it's rare but there have been two documented cases of sperm being produced while also having normal, functioning ovary.

In one of the cases a phenotypically male individual both successfully fathered a child with male gametes, and they found evidence he had in the past ovulated, so he produced both male and female gametes. Usually in these cases it's the production of male gametes that do not occur.

Walsh claims "any biologist worth his salts" will affirm the definition of biological sex as being just the gametes that the individual produces, but not only is this not the only way biologists define sex, it's not relevant to how sex and gender are defined outside of biology. Biologists often have multiple definitions or concepts, their theories are usually more pragmatic than philosophical (intended to be useful rather than total in their scope), and this comes up in all sorts of places - for example the definition of a species, the definition of life (is a virus alive?), and so on. Biologists are rarely dogmatic like Walsh, and they don't apply a theory that was developed for pragmatic purposes in the context of biology as dogma in all contexts (like how we should handle social policies or how we should think about gender, etc.). This misses the entire point of the theory and the context in which is meant to be applied.

To make this point more salient, Walsh believes someone with XY chromosomes with CAIS like Alicia Weigel is a man and must use the men's restroom. Alicia is not just a woman socially, she looks like a woman and Matt Walsh wouldn't know she had XY chromosomes by looking at her. Forcing her to use the men's restroom would obviously violate the social norms he is trying to appeal to when bolsteringhis anti-trans rhetoric. There is an obvious mismatch between his account of her biological sex and what he would intuitively think is acceptable in a social context based on his strict assumption that your gender is only your biological sex.

Anti-trans (and anti-intersex) activists like Matt Walsh don't actually intend for their policies to have common sense outcomes, they are designed to criminalize and terrorize a group of people out of public existence, they use genocide language like "eradication". So it's not a flaw of his policy that Alicia would legally only be able to use the men's restroom, it's the intended outcome, so that she will either avoid being in public and risk using public restrooms, or take the risk of being caught and then facing going to prison (potentially a male prison if they decide her sex is actually male because of her chromosomes). In places like Florida, trans inmates are being forcefully detransitioned and subjected to conversion therapy (which is also debunked as not only ineffective but resulting in increased risks of self harm and suicide, and worse outcomes in terms of mental health, drug abuse, etc.).

Besides, even if you wanted to believe Walsh's definition of sex as perfectly binary, his definition also doesn't answer which of the two sexes a person is if they don't produce any gametes.

For a more accurate and scientific portrayal of how sex is being thought about, this Nature article is a good place to start.