Interesting tactic, but boycotts probably don't require much training...
That said:Since he violated store policy, it's Walgreen's right to terminate his employment, despite the fact that he saved them some $ and likely his coworker's life.
Working in a location where carry is not allowed by anyone, employee or otherwise, I'm not terribly surprised at the company's reaction - would set a "dangerous" precedent to allow him to retain his job.
So to perhaps keep this alive for T&T purposes: What do I do if some random BG comes in? Hide under my desk with a letter opener, hope for the best, and be a breathing witness after the fact.
Dammit, Jim, I'm a librarian, not a security guard!
"The best diplomat I know is a fully charged phaser bank" - Montgomery Scott