If it's not legal for me, why is it approved in my FOM?

Just because something is unusual, doesn't mean it's prohibited. FARs give the Capt a ton of leeway to safely operate a flight.
If you, as the Capt, feel landing a plane at a non-towered airport without a vis report is beyond your capabilities, then don't do it.

I don't think there's a company out there that's going to relish the monkey wrench you just threw into the system. But, I'll gladly open the pocketbook if the company over-reacts and tells you to hit the street.
(Especially since most non-towered ops are in the midnight-5 timeframe--have to think a divert might put you beyond duty limits, limited turn possibilities, and how do you get an "approved" weather guy out to the field to fix the problem you diverted for. Can't you just see the film running on CNN-certainly shouldn't consider the media as part of your decision making. Although I guarantee the company will consider it and likely overreact.)