Agreed. I watched that video too, and ... it's a data point for the MacBook, but not really solid evidence even for it, and certainly not for the MBP. They could be putting old keyboards in as replacement while they clean out inventory, and then start putting in a new and improved design. Or they might not have an improved design at all, and could end up doing exactly what people fear. Or like you said. Or several other possibilities. The thing is, we don't really know yet, and speculation (like you said) is not super productive. Would be kinda nice if Apple could communicate a bit more on this issue, but I'm not holding my breath.Pure speculation on his part. The replacement keyboard could have some improvement to certain components, or some other minor manufacturing change, that he's completely unaware of.
There's also (at least implied) testimony from the genius that there was indeed a new design. But the fact that a new design keyboard didn't end up in this guy's laptop doesn't automatically make Apple or the genius liars. There are many other possibilities, and we're only doing ourselves a disservice if we ignore all other possible options and automatically assume people are liars when something odd happens. Some people are, but most people aren't.
YouTube and internet in general is a weird place, where people often completely lack the ability to draw conclusions properly from available data, or avoid doing so when the data doesn't support a conclusion -- and they still end up making "instructional" or "investigation" videos. I'm not always sold on science as being the one and only truth, but the scientific method is a fairly proven method of moving knowledge forward for the whole of humanity. YouTubers and Apple commentators would do well to learn about it.
(In all fairness, there are also many YT videos and creators that are absolutely amazing, and are incredible sources of solid knowledge.)