I don't know the trails involved in this tragedy but the riding conditions, based on NWS data and what the sheriffs and family are reporting, would be normal winter riding conditions in the Pacific NW. I spent 20 years riding all winter in 34 degree rain and 29 degree sleet with standing water everywhere. I have been on six or eight hour rides in miserable driving rain, cold and wind. Those rides were on steep tight switch back Cascade Mountain trails where you hope the slope is only 20 degrees. I have even seen 29 degree rain and sleet on July 4th at 6,000 feet while riding in the Cascades. That's mountain biking at 47 North.
I'm not trying to brag about riding skills but am just pointing out that IF you are well equipped and experienced then rain, fog, cold, snow, sleet, wind is no big deal and in some places, is considered a normal riding situation.
I think the accident victim was foolish to go with so little equipment or preparation. And, even though I did a lot of winter time solo riding in Washington - that trail in those conditions would not be a place I would solo. But, this rider did solo, did hurt himself, did call for help and did need help. Then someone made a decision to not provide that help and that I do not understand.
Given all the above - I just don't see how the local rescue folks were able to say the conditions were too difficult and dangerous for them to try to find the rider. Oregon and Washington rescue groups regularly spend two or three nights in a row searching in sub-freezing rain, snow, sleet, and very heavy wind. I just don't understand what the rescuers in this event were so concerned about. Pacific NW rescue teams go on foot and hike dozens of miles in terrible steep, wet, slippery, and pitch black trails on a regular basis.
A close friend was a dog handler for Search&Rescue and thought nothing of spending a couple days walking, slipping, and sliding in mud, snow, and wet vegetation while searching day and night. I know of at least a dozen rescues she went on that commenced at mid-night with exactly the same phone call this victim's wife made to the sheriff. She and her dog would then spend the whole night searching on foot because there was no possible access for any wheeled vehicle.
My reading of the Sheriff's response was that they were counting on mechanical devices for access and did not consider a hiking approach. Experienced S&R hikers, with modern lights, can easily cover 3 miles an hour and would certainly have found the rider in the early AM - if they had been dispatched when the wife first called to say her husband had called her to report he was lost and dis-oriented with a head injury. S&R should have been on the trail hiking by 10 PM at the latest.
Sorry to be so negative but my extensive experience tells me this tragedy did not need to happen for many reasons.