Originally Posted by Rust
That trailer-description might be fake, but it's entirely possible that Jonathan wont be the super-friendly all-saint he's usually depicted as. He might be more of a realist and pessimist while being overprotective as well. Kinda like in Birthright.
So him saying that line to Clark might be a pessimistic way of saying he wont be able to save everybody. Though that line makes it sound like he shouldnt even try, which is stretching it.
It's definitely possible, I mean if he does say maybe how do we know in the film he might not say maybe then think and say no but you have to be careful if people discover your secret blah blah blah.