We all lie every single day. Lying is one of the best things you can do sometimes, as any father and husband can tell you.
This isn’t necessarily as easily-forgiven as, “Yeah, buddy! These banana muffins are delicious! Maybe you’ll grow up to be a chef!” but it’s not really off the charts hideous. Also: there’s a slim chance it’s not a lie anyhow. You never know. Assuming it is:
Maybe on the scale, being totally honest and admitting the misdeed would have been “better” and even made HIM feel better. But on a given day, we don’t always have that level of change in us. It’s a particular kind of bravery and we’re not always going to be our hero selves. Better to advance with a step forward and a hesitant shuffle back than no step forward at all.
I suspect strongly that if it IS a “cover-up story”, that at least he’s probably not going to steal stuff again. It’s evident that he didn’t get anything positive out of the experience.