Plenty of things ought to be said in life but there are nearly as many that do not need to be if one stops to think about them for a moment, or to consider their presence without the verbalization. Edmund doesn't need to apologize because it wasn't his fault in the first place, and as far as Peter is concerned that's that on the subject.

"Snowshoeing, if you like," he replies dryly and continues with barely a breath, "But no hurry." That is both true and terribly the opposite, but the latter cannot be helped. Even as Edmund could vanish, so too could Peter, could Susan, could Lucy, could Caspian. Any one of them. All of them. So it only makes sense enough to decide there is no rush on what precisely to do with one's time as long as one does something. Anything is better than nothing, barring a few of the obvious exceptions to the rule, none of which the Just is likely to endorse or involve himself in anyway.