It's election season, which brings out the yard signs, which brings out the people who steal and vandalize yard signs. I'm sure you've seen the stories in newspapers and the postings on social media. Maybe you've had first-hand experience.
I try not to be too judgmental. I can imagine how in a moment of passion (or, more likely, drunkenness) an otherwise reasonable individual could have a lapse of reason. Naturally, it would need to be followed up with an apology and full restoration. It's forgivable, right? Yard signs are by their nature ephemeral.