What do you think about heightism being worse than racism

I think for the argument to work as it being "worse", it would have to minimize the modern version of racism completely, which isn't how reality is.

Racism wasn't systematic, it is systematic. It wasn't more common back then, it's still common. To say murder based off of racism "rarely happens" isn't really true, it's just not to the degree it used to be. But it doesn't mean it rarely happens, it means it's less likely to happen than it used to be.

With that being said, you can talk about heightism and how it effects millions of people (especially men) without comparing it to another social issue. They're just so completely different issues that it's almost comical to compare the two.
As @Flint and I are both American, I imagine our experiences are heavily rooted in de jure vs de facto concepts, especially with race. We just observed Juneteenth here, a holiday celebrating the day slaves were told they were free. Not the day they were freed, but they day they were notified, because even after the government abolished slavery, the people of Texas collectively agreed to just not tell them for two and a half years that they were free.

At the end of the day, a piece of paper signed by the president didn't really do anything until people were forced to change. I think this is where comparison of the two topics can get dangerous. I've seen some reactive things some guys have said about how women deserve to suffer (or at least be denied happiness) for not being immediately attracted to a short dude.

I will (gladly) say that I think plantation owners deserved to have the army come in to force them to free their slaves. They needed something unpleasant to change their actions because their perspectives weren't changing. I don't think it's safe to have a similar mindset with women needing external unpleasantness to change their actions if their perspectives won't change.

That said, even after the slaves were freed there was a century of laws criminalizing black people for being unemployed, speaking to women, or being outside after sundown. If short, there can be barriers to entry for many aspects of life, but not criminalization. Exclusion is terrible, but it's not active targeting.