I very much doubt that Edward would have repeated the thoughts of the last person who spoke to him if they had been Socialist. He remained right wing in his views (and anti Semitic) all his life. (There wouldn't have been too many upper class English people who referred offensively to 'Yids' as late as the 1960s, long after the Nazi Holocaust and in conversation to a Jewish woman, at that) He remained wedded to the thought (like Oswald Moseley) that Britain need not have gone to war with Germany after the war and until he died, and in fact was reproved by George V for making a speech to British ex serviceman espousing this in 1935.
I think we are dealing with different topics here:
1) The idea that Britain didn't have to go to war with Germany
in 1914 is not that out of the mainstream. In fact, in the centenary of World War I, we saw several well-known (and controversial) British historians, including Niall Ferguson who now lives in the US, defending precisely that point of view and almost blaming the UK for WWI. I happen to disagree with that opinion and, in most debates, that position is normally on the losing side, but it is, nonetheless, again a relatively frequent opinion in
some circles. I can't tell how people felt about it in 1930s, but, in that respect, it wouldn't shock me David/Edward also thought that WWI had been an unnecessary war.
2) Likewise, the idea that Britain did not have to go to war with Germany in 1939 and, even more so, that Britain should have made peace with Germany after Germany de facto "won" the war in 1940 again was not an eccentric opinion at the time. In fact, it was the view of a considerable section of the British government and, I would dare to say, with respect to a peace agreement, it was something that even George VI would have gone along with (after all, Lord Halifax was his preferred choice for PM). Thankfully, as it happens sometimes in history, an unlikely protagonist like Churchill and a bit of luck combined with wrong decisions on the other side (in episodes like Dunkirk and the Battle of Britain) , were able to steer events in a different direction which, in the long run, was good for Europe and good for the world. Again, however, I wouldn't fault David/Edward too much for thinking like that at that time, if he actually did.
3) A third and completely different thing from the two points above would be David/Edward being a fascist or a Nazi sympathizer, or advocating fascist government in the UK or Nazi-like policies with respect to Jews or other minorities. I don't think there is any
hard historic evidence of that being really true, although there are suspicions and there is this often common narrative in
fictional literature where, if Hitler had succeeded to invade and occupy the UK in 1940-41, Edward would have gone along with a puppet fascist regime as long as he was reinstated as king with Wallis as queen. My point before, however, was that, if Edward was indeed a fascist or a Nazi, then, unlike appeasement in (1) and (2) above, his opinion would
not be mainstream. The mainstream appeasers were against the war, but they were not fascist.
