He's trying to generate a post-hoc justification for an inaccurate statement, there's nothing more to it than that. Still, self-identification matters and I wanted to see if he'd cross the Rubicon and try to force the white identity on groups that don't want it.
Bearing in mind his linchpin example - Arabs - are neither perceived as nor self-identify as white [1], it's bizarre to suggest that it follows that the Japanese, a separate case anyway, must also be white.
Add to that his conflation of ethnicity with race [2], and it might be the single most stupid comment I've ever seen on HN. Just say "OP meant to say black", there's no need to construct an alternate reality in which non-white and black are synonyms.
"many in the MENA community do not share the same lived experience as White people with European ancestry, do not identify as White, and are not perceived as White by others."
That doesn't even follow from your own previous sentence - it would have to mean "not black or latino".
Have you asked any South East Asians if they consider themselves white?