Just pull up the Wikipedia page about LGBTQIA rights, show the anti-trans bills that have passed, the death threats against agencies that show any level of support.
I wouldn't even try to argue that cishet men aren't oppressed because: A. The burden is on the person making the claim, B. You can't prove a negative, and C. It's irrational to think that they are.
I'm a cishet man myself, and while I've experienced a lot of hate for being gay, there has never been a time I've received any hate for being cis. That's just ridiculous.