Of course it all depends on many factors, location included. I thought it was obvious, but apparently judging by the down-voting frenzy it is not.

Ironically enough the only time I walked out of public place over a left behind bag was in Vancouver. A hippy-looking Jesus person marched into a Starbucks, dropped his canvas bag on an empty chair, paused for a second and marched out. He was completely spaced out, not focusing on anything, and it all looked as odd as it sounds. It was on Robson street around lunch time. So I got up and left, and do tell me that it was not reasonable thing to do. The guy was outside, just outside the entrance, yelling at someone over a cellphone, and that explained his behavior. But without knowing that it could've been something else.

And, yes, I am familiar with the term "security theater".