You’re entitled to your hill, but as linguistically correct as you may be, linguistics take a back seat to common usage and national variance.

Nationalized and nationalised are both English terms. Nationalized is predominantly used in 🇺🇸 American (US) English ( en-US ) while nationalised is predominantly used in 🇬🇧 British English (used in UK/AU/NZ) ( en-GB ).

It’s a Z in American English. Both spellings are correct.