My interpretation is that Nasu's romanization of preference changed with the years, but this is one of the points he's weirdly anal about consistency.
Altria is Altria because Google Translate gave him the cigarette brand name in 2010, and it stays Altria because the name was officialized by a material book.
Likewise, my bet will always be that Sizuki Soujyuro is spelled like that because that's the spelling Nasu already put in the high school Mahoyo notebook that will never see the light of the day.