A more realistic scenario that surely must have been considered is this:

They make a strategic investment in the DRAM maker. It's the same idea as buying an equity stake or entering a JV with a flat-panel maker. Or deploying cash to provide the latest EUV tooling to TSMC.

Large famous-brand computer maker has no expertise in running a fab.

I could punch holes in this idea right away. But it seems better than "tilting up your own fab".