They might also be building a case against Superman so that Lex has more sway turning people against him in the sequel(s)

But for a character that's been a known quantity for generations, it was tough to see him not know the basic shit. And you gotta admit that they did kinda establish him as having a natural instinct for protecting people and doing the "right" thing. So I still say it was out of character, even on the film's own terms. But I see where you're coming from.