Hmmm, would I obey that order? Let me think for a nanosecond- FUCK NO! They'd have to fire me, if it came to that. That's the point when I'd find another career. I took this job to help protect citizens' rights, not grossly violate them, as that order clearly would.
As far as fearing for my life if I was stupid enough to obey that order, hell yes I would! There's way too many law-abiding folks out there with guns who would also draw the line in the same place. After the first few search warrants were served, the rest of the people would make their decisions and there would be some really ugly gunfights. Eventually, most departments would decide that it was too expensive in terms of negative public relations and just flat officers killed or injured. I also think many departments would refuse to conduct house-to-house searches for guns.
That being said, I don't really think we'll ever see that day. The anti-gunners know what would happen, that's why they've taken the route of gradually increasing restrictions while teaching our kids that guns are evil and there's NEVER an excuse to use violence, even in self-defense. The social engineers may be evil, but they're not stupid.