Not the same as invulnerable--I can kick Clark's ass.

[She sighs.]

Clark freaked out because it doesn't matter that he keeps getting shot with kryptonite, or magic--or died. [Her voice gets audibly strained, but she pushes past it.] If he bleeds, something's wrong.

It doesn't excuse him--I'll deal with him later--but it's why he won't get what you tell him. Not really, anyway.