To be fair. They're not advocating preparing for Armageddon with supplies, at least they didn't in my congregation when they had similar announcements and skits. They are actually being practical and helping the JWs prepare for natural disasters. I actually think it's a good thing and wish other groups would advocate the same idea.
There probably is a bit of selfishness on the borg's part in doing this. If the individual JWs have already set aside disaster supplies, the borg will not have to provide them as much when a natural disaster strikes. Since disaster relief is the only way that the borg is "charitable".