Also note that 100km is the minimum height to be "in space", not the minimum height for achieving orbit.

That doesn't really mean anything. You could achieve an orbit at a lower altitude if you wanted to, it would decay faster, but you could do it. The 100km karman line is an arbitrary thing, there is no solid line where on one side you can orbit and on the other side you can't.

Finally, I disagree with the note that having "enough fuel" to reach orbit means they have demonstrated such capability

Well this seems like a bad semantic argument to me. I guess the question is, what does it mean to you to "demonstrate capability". Like, for you, what would be the difference between demonstrating a capability to do something and actually doing that thing? How would those two things look different? Or in this specific case, how could they have demonstrated that capability without putting their rocket into a stable orbit (because it would be negligent to do that with this prototype rocket)?

Given what they have done, is there any reason to doubt they could have gone a little bit further? And conversely, was there a good reason to stop where they were, or do you think they would have gone further if they could have?