One issue I've had with swapping fans for Noctuas is the airflow matching. The louder fans aren't louder just because they're lower quality (which they definitely are), but also because (almost always in my experience) they force more air through.

That unit from the article sounds very temperature sensitive. I'd be wary of throwing a precision unit like that out of spec and out of calibration.

FWIW I've noctua-swapped so many things including an oscilloscope.

He mentions that he's running it in an air-conditioned studio, so presumably if the unit's datasheet lists an environmental range warmer than that, it has plenty of cooling headroom in this environment.

The last rubidium oscillator I played with, had to heat the vapor cell within the physics package, but then prevent that from overheating the rest of the unit, so it specified mounting to a heatsink. There was no heatsink recommendation given, just a certain package temperature as reported by sensor value X in the diagnostic data page. Get below that and you're golden. Get too much below that and you're wasting extra energy in the heater. Which is harmless, it just drives power consumption up.

So depending on how the unit's thermals work out, a slightly less aggressive fan may end up being mildly beneficial.

You can just look at the airflow charts and buy accordingly?

I wish Noctua fan fans realized they're fan equivalent of "unsafe languages such as C++" Rust fanatics. Even actual Rust fanatics would see how that kind of attempted advocacy is counterproductive.