This is a standard defense tactic, sometimes called "What-about-isms" and is a Trump favourite, as it happens.

There are some topics for some people where they'll dig in and won't see reason whatsoever. China (for Chinese nationals) is a common one when you can bring up any number of subjects, the "re-educations camps" being just one.

But, but, but... what about US internment of Japanese descendants in WW2? Or the genocide of Native Americans? Or slavery?

That's how it goes. Sadly.