This is a discussion of the current state of affairs, not, for example, a Searle-like claim that understanding can not and will never be achieved. To substantiate a claim of 'no true Scotsman', I think you have to present an actual case where you think a machine has achieved understanding, but which is being unreasonably dismissed.

Ironically, your last sentence has 'no true Scotsman'-like reasoning, along the lines of 'no true AI sceptic would fairly evaluate a claim of machine understanding.'

BTW, I am not a skeptic of the potential of AI, though I am skeptical of some claims being made.