It's a way to avoid issues. For instance if you support gun rights and something like this happens people you know might challenge your stance, then you will have to explain why the right to bear arms is important despite such very rare incidents. They might actually challenge your views and you will might have to actually think about what they are saying and formulate a reasonable response. You might even end up questioning your own beliefs. But if it was all a "false flag" then no problem, there is nothing to deal with.