"Theory" and "hypothesis" are pretty interchangeable in colloquial usage, and the post's tone is very colloquial. On top of that, there are things referred to as hypotheses that have empirical evidence, like the amyloid beta hypothesis. There is empirical evidence that supports it, but there is also evidence that doesn't, and it's an open question (depending on who you ask).
I don't think it shows that the author lacks the ability to discern state of the art research or is making wildly unsupported statements, I think they were using plain-English terms to describe a state where there's a lot of uncertainty about the physical mechanism as opposed to say, how a car engine works (which at a certain point relies on theories of physics, but they're theories that are almost universally agreed upon).
The bizarre CS idea of using "plain English" as a propagandic thrust to infantilize complex scientific theory is suspect. Let's eschew the idea. "Plain English" is Orwellian dumbing down.
There is a general agreement which links ontogeny and phylogeny, details working memory, its relationship to the allocortex, and subsequent episodic memory. So the neural correlates have been worked out.
The working memory and episodic memory papers in the last few years have isolated the correlates, we a have a fairly empirical neurobiological description of memory function and process.
What we're lacking now are the molecular mechanisms.