I have been lurking here a bit and just wanted to put my thoughts in here. I actually wrote about this before where I discuss that Namor is Marvel's and perhaps Comic's very first biracial and east Asian coded character. His journey through comics does not start with the anti-japanese comics of the WWll era. His people are an indigenous coded people and Namor while he may be of Scottish descent on his father's side who is most likely scottish-american,
Namor is not white. This isn't just a throwaway thing that happens, it starts in Namor's first comic (and in the extended edition when marvel mystery comics started). Namor frequently says things or mentions his tribe regarding the Atlanteans, and Everett wrote how Namor was warring against the 'white race' Namor was a character whose people have been harmed by the white explorers who came onto their territory and their actions killed atlanteans.
Later Namor is recruited into the war (this reflects how japanese-american soldiers volunteered or were drafted) this era of comics is extremely hard to read due to the nature of the writers pushing the anti-japanese sentiment. Namor's character was transformed from a man seeking justice for how his people were treated to a character whose own looks were remarked upon in racism and used to spread racism. Then later Namor's character is changed again, back to the prince whose people were always under attack and whose homeland was destroyed by pollution, and war. He was still coded as an east-asian character in the later comics.
A few comics to look for in example of are: Marvel Mystery Comics (1939) #1-4 . Sub-Mariner Comics #5. Avengers (1963) #7, The Defenders (1972) #1, Tales to Astonish #95.
I wrote out my thoughts much better
here. It includes panels from the above mentioned comics.
However if you want to call a character xenophobic I would suggest you look beyond
one era of comics that were extremely prejudiced towards japanese people before deciding that the character is in fact xenophobic and not actually used to spread war propaganda especially since Namor's character did not in fact ever start out that way. You can take any character and find something that someone has written at some point that is wrong, and this is especially true of Namor since he has been around since the start of comics.