You can use my subscription to het+ if you want, I don't anymore. (Het+ is a term for cool people that have grappled with their sexual orientation and turned out to be straight. Much cooler than normal hets)
This is technically correct, but I believe his point was that cishet people get to experience heterosexuality as a default mode which is passively affirmed throughout most of society, whereas trans people often have more alienation from that passive affirmation, both in their gender and in their sexuality. If a trans man and a trans woman are attracted to each other, are not attracted to members of their own gender, their relationship is a straight relationship, but it can also be a queer one and they’re more likely to see it as such because of their relationship with trans-ness.