Are you proposing that all of physics is untestable because we don't know how to test it inside of a black hole?
Yes. I'm saying the the total set of all physics is currently (and likely to remain) untestable. Which isn't to say that science cannot handle it. We use principles like Occum's Razor to say that if it is the best description of what we can observe, then we assume (pending further disproving) it is true.
Which works out great. I mean, "truth" is a nebulous concept. One can construct a universal coordinate system that treats the earth as the unmoving center, and has the sun moving around it in strange shapes. And, in fact, that's the coordinate system we use through most of our daily life (folks at NASA, SpaceX, etc. excluded). But we recognize when it becomes more convenient to have a different truth. Also, similar to how I've never concerned myself (outside of class) with relativity, but GPS engineers had to.
Heck, even relativity wasn't testable when postulated. It took like 40 years to conceive of a test.
So I suppose my entire point was against the unreasonable goal of testability for all facts.