Anyone confused as to why JKR is against asexuality, first you must understand that TERF ideology depends solely on maintaining societal binaries, and when TERFs talk about sex (as in, intercourse) they need to categorise sex in the same boxes they place gender. For example, sex is between man and woman for procreation purposes, and when it isnโt between man and woman, then binaries must still stand. Biological men must have sex with biological men, and only be attracted to perisex cis male genitalia. Biological women must have sex with biological women, and only be attracted to perisex cis female genitalia.
Anyone with sexualities outside of these binaries are inherently a threat to TERF ideology. Bisexual people are a threat to the ideology, because they blur the lines of sexual attraction and the seemingly pressing need for specific genitalia. You never see JK Rowling include bisexual women in her crusade against trans women in womenโs spaces, because her slogan of โwomen donโt want to sleep with women who have penisesโ probably wouldnโt work nearly as well if one is to include women who donโt have a particular preference (obviously, bisexual people can 100% have a preference, as can lesbians, but JK Rowling isnโt exactly one for nuance).
Therefore, asexual people are also a threat to this binary by simply not engaging with it. By not wanting to have sex, she again loses a demographic of people who give a shit about genitalia, and that is all that matters to her. The only sexualities that she cares to include in her โactivismโ are the ones that can be used to maintain biological sex. Lesbians are used as a weapon, while all other sexualities are thrown under the bus.
It shouldnโt come as a surprise to JKR fans who identify with these sexualities that eventually she will turn on them too. Donโt say we didnโt warn you.