They use it as a canard but it isn't even relevant.
"Intersex" is, outside of strict medical terms, a misnomer. It does not mean "two genders" or "two sexes", it means that someone has traits of both sexes. They are still one sex, male or female, and most surgery used to correct it is based around figuring out (if born with a penis and vagina) which set works and which doesn't. It's quite rare to have both working.
It has zero to do with being trans. Intersex people are the sex they present as, the sex they present as being their chromosomal sex. Troons just use it to say "see, sex and gender isn't binary/fixed in nature, therefore being trans is XYZ" Intersex people are not getting sex reassignment surgery. They get orchiectomies because otherwise they will have hypergonadism in puberty, or they get drug regimens to prevent gigantic tits as a 14 year old boy. They don't get gash wounds or thigh cocks.