Strange that you would feel a need to debate this.

Triplets have nothing to do with time signature. Just that point reveals lack of experience in this area. Triplets exist in any time signature or lack of one. They are about beat subdivision.

I could explain each of these points in greater detail but I am not compelled to take the time. Playing scales to meter is a common technique.

And if I asked even a professional to sit down right now and whip out, say a melodic minor in five flats, four octaves at a quick consistent pace, many would indeed need a quick try first. They do get tricky indeed.

Professional musician here. That would be trivial to do, even on my weaker instruments, and even with triplets.

Though just give me the tonic name, no need to call it five flats.

Edit to add: To be fair I'm about a decade further in my career than someone going to study music for the first time.

That’s great to hear, but allow me to offer a common example. Ask a pianist to quickly play four octaves of melodic minor in thirds, and especially as one hand is ascending and the other is descending at the turning point, and there are two different modes being played simultaneously, many will indeed miss a note. Now make it a less common key, and you can see why it can be tricky for some. Certainly not everyone, for students yes and even some experience pianists may need to practice a bit first.

This kind of request is very common at many music schools for these kinds of exams.