I'd argue it wouldn't necessarily even mean that.  I habitually use two spaces after each sentence and PCs were relatively common in my youth.  Moreso than typewriters in any case.  I've certainly never used a typewriter for anything other than screwing around for the sheer novelty of it.

It may imply, as happened with me, that their English teacher may have been of an age where they were taught to type in that fashion and that's simply the habit they passed on to all their pupils.  Never underestimate the power of indoctrination.  

Two spaces is not strong evidence.

It indicates that Satoshi probably trained on a physical type-writer prior to digital processing, where double-spacing was common. But we could already guess that Satoshi isn't young any more. https://www.cultofpedagogy.com/two-spaces-after-period/

I personally think that his double-spaces means that he resided in the American West, where double spaces held on culturally for longer than in other parts of the world, and which matches several of his other behaviors.