The word stranger is commonly used to note the Gentiles, or such as were not of Israel's race; but sometimes it notes those that are not of the priestly race, as Exodus 29:33 Leviticus 22:12,13; and so it seems to be here. And if any of the kings were anointed with this oil, it was done by God's special appointment, who may dispense with his own laws.
Related Commentaries of Exodus 30:33
Exodus 30:33
33 Whosoever compoundeth any like it, or whosoever putteth any of it upon a stranger, shall even be cut off from his people.