Article is bias'ed as heck. As you pointed out, why would Samsung WANT to use Apple's implementation of Samsung's SCREEN technology. It's ridiculous to even claim it' Apple's "screen technology" when they are using someone else's displays.
Your point is valid, but it raises an important counterpoint wrt innovation.
You can invent a product, but you can also invent a process. When you invent a product, it isn't necessary that you also own the invention that produces it. If it were, it'd be harder to sell process innovation and harder to improve the construction of products.
In this case, Samsung invents the machines and manufacturing process -- setting the the design and quality bar for components. Apple invents the use case and the spec sheet -- the design of the end product. Samsung also makes screens for their own phones, but those engineers produce their own use cases and spec sheets.
Samsung announces some new innovation -- with it, they can build pixels that are smaller, more efficient OR more colorful (but not all three). They choose to use that innovation in their own phones to do one thing -- higher resolution, because that's what the designers of their models would like to sell, and also because to take advantage of more color they'd need software changes they don't yet have.
Apple puts together a spec sheet asking for more colorful displays using X wattage and Y thinness, etc, but keeping the resolution "low" (or "good enough for Retinas," as they'd have it). They put this out to bid and Samsung beats the competition -- they can provide more displays using Apple's specs using their process than the competition.
Now this is not an off-the-shelf display. It's a custom build product. It uses Samsung's process and Apple's goals. Apple can take those goals to any screen manufacturer they want and have displays built, possibly using a different process.
Who invented the technology? In a very real way, Samsung did, since you can't have a product without the process. Who owns the technology? Legally, Apple does, it's their design.
Could Samsung build this display for their own phones? Well, no, but they could make one extremely similar to it -- if their engineers asked for it. Would they ask for it, though? Is trading expense and pixel count for colour quality something their users even want?
