It matters because the theory in this case wasn’t that both light and tennis balls behave like a particle. It was that light behaves like a tennis ball. As such, demonstrating that tennis balls succeed or fail to display certain light-like behavior is certainly an important result.
So, the most controversial aspect of pilot wave theory is the idea that a classical system can reproduce some phenomena considered only to arise in a quantum one. The 2006 result was important because it appeared to definitively prove a classical system could do just that, and for one of the most famously “weird” quantum results. How accurately it correlated with a hypothetical pilot wave based quantum reality wasn’t really relevant. And if the original result was important, then the failure to reproduce it is also important.
More generally, scientists can argue about theory, mathematics and the “deep” stuff until the cows come home. But what actually advances science is experiment. It may not always be the most glamorous or exciting work (CERN notwithstanding). It can be an expensive, years-log slog to add a single negative data point against an idea a theoretician dreamt up in an afternoon, and which they’ll dismiss as irrelevant, or avoid by tweaking a single equation. But it’s, quite literally, the part of science that gets results.
One excercise that is fun to do: reduce the Schrodinger equation by splitting the real and complex parts, the figure out how to build a damped spring system that can support the wave. My interpretation of quantum mechanics is that everything is springs and dashpots in the end.
This is great, I think I'm going to explain it using your method from now on.
Edit: I love that there's a segment of people in the QM community approaching these "very serious" thought experiments like Schrodinger's Cat (as the classic example), instead using absurdism to produce equivalent but blatantly ridiculous results. Like the Surrealist reactionary art movement but with the often insane results QM produces. Sometimes I think string theorists need a group kind of like this too.
My favorite of these types of bizarro QM communities is that of the "holographic fractal" universe. Nassim Haramein[1] being one of the popular figures of this movement. If you're willing to sift through the mysticism, the r/holofractal subreddit has some interesting ideas to chew on during an otherwise dull lunch break.[2]
So, the most controversial aspect of pilot wave theory is the idea that a classical system can reproduce some phenomena considered only to arise in a quantum one. The 2006 result was important because it appeared to definitively prove a classical system could do just that, and for one of the most famously “weird” quantum results. How accurately it correlated with a hypothetical pilot wave based quantum reality wasn’t really relevant. And if the original result was important, then the failure to reproduce it is also important.
More generally, scientists can argue about theory, mathematics and the “deep” stuff until the cows come home. But what actually advances science is experiment. It may not always be the most glamorous or exciting work (CERN notwithstanding). It can be an expensive, years-log slog to add a single negative data point against an idea a theoretician dreamt up in an afternoon, and which they’ll dismiss as irrelevant, or avoid by tweaking a single equation. But it’s, quite literally, the part of science that gets results.