It's your IOMMU, you can do what you want with it. Maybe you need to write heaps of stuff to take advantage of it, but what's new there?
The only thing you're getting by saying "no IOMMU" is "I want any devices in my machine to be able to do anything, not just what I want them restricted to".
Okay, but he's specifically brought it up in the context of a computer's owner doing something that the software vendor (and also myself as another gamer harmed by cheating) would prefer he did not.
> unless you find it terrifying that owners of hardware have control over their hardware
I mean that the presence or absence of an IOMMU doesn't impact whether owners of hardware have control over their hardware.
It just means that the owner of the machine is able to limit what memory the devices in their system are able to access, in the same way that MMUs limited what memory every process on your system could access.
The only thing you're getting by saying "no IOMMU" is "I want any devices in my machine to be able to do anything, not just what I want them restricted to".