I never really liked that kind of history changing. There was never anything wrong with Rockman's original stories, so why did he have to be retconned into just some ordinary guy? The Abyssinia stuff made him interesting, why remove it? It's no more far-fetched than all the other subterranean characters still appearing in Marvel comics today, so why change Rockman?

As for Subby's "American patriotism", the first story in Sub-Mariner Comics #1 gives a good explanation for his nazi hate, and since he was generally hanging out in the US in those days anyway, I don't really see the problem. He was influenced by what he saw and experienced, and took the side of the people he actually spent time around.

Out yonder, under the shining vault, among men the saying goes: 'Man, be thyself!'
At home here with us, 'mid the tribe of the trolls, the saying goes: 'Troll, to thyself be-enough!'