I guess he also believes that 50 MHz or so signals can be measured reliably on a 40 MHz (on paper at least) scope.
That's more than good enough for the purpose of checking interference
https://news.ycombinator.com/item?id=47931024
PS Now that I’ve taken a closer look, this is even sillier than I first thought.
He’s hunting for 50 MHz ghost signals by connecting his PCB to a breadboard using (crappy) wires that are at least 10 cm long. And he’s connecting the scope probe to the breadboard (or those breadboard wires).
And if I’m not mistaken, he doesn’t even bother to connect the ground lead of the probe.