Hrm..... agreed here. If one doesn't feel safe, one shouldn't bike or drive -period. I rather liked the fog a lot, but was going slower than usual, with blinkis, lights & all. I don't know about the trails near the rivers and around the bridges, but the streets seemed safe to me (all flat streets).
Maybe this is just me, but even when it rains, snows, or there is fog; I feel --safer-- on my bike than on a bus or car, because I can react faster, go slower/faster as applicable, and can go into the sidewalk or 'park' the bike if I don't feel safe.
But that's just me..... riding at 6am is a whole-other animal than riding at 8-9am when I go to work.... in the mornings I'm trying to not leave my house until there is enough visibility, while in the pm I have to drive in darkness, but then I lit-up like a christmas tree....
Ultimately, I feel safe and I know-and-look forward to the ride regardless, I do it