What then is the research barrier they need to cross? I'm genuinely curious. This seems more "researchy" than a lot of other items I've read (such as optimizing a planar antenna geometry with included matching network et. variants) to me, but I'm perfectly fine with a very blurry engineering/research line.

There is "research"--in which one is poring over an existing body of knowledge and possibly "tweaking around the edges" to investigate properties described therein, conducting surveys to gauge response (e.g. "market research"), and the like. This kind of research is a superficial investigation into well-established, well-known subject matter, possibly with an interesting approach or to find a context-specific answer to a question, but not one that fundamentally adds to the body of knowledge.

Then there is "research"--in which one is exploring a new, known but unexplored, or a known, previously investigated but complex problem in a novel way with the intent to expose previously unknown properties and add to the body of knowledge. This is the kind of "research", e.g., physicists, mathematicians, and some engineers do.

I hazard a guess, without knowing for sure, the parent sees a "barrier" between these two kinds of research, and that he'd place this article in the first category rather than the latter.

Yup. This is basic engineering as taught early in any mechanical engineering curriculum. That's all I meant. It's still cool and worth while, I just don't see anything that separates it from any other application of basic theory. It's no more research than building a ruby on rails website.

It's not scientific research, but the word "research" covers a much broader set of investigations than just science. For example going to the library to look up sources for an academic paper is commonly called research.