Seatbelts and motorcycle helmets have clearly defined and measured benefits in preventing and ameliorating serious injuries. Bike helmets have few if any benefits in reducing injuries. Putting people off cycling probably has much more adverse health impact than the vanishingly small number of serious injuries prevented by cycle helmets.
Sorry no photos. However, the hardest part of Cneifon ridge is the first 80ft. It's probably about Mod. It's quite steep, but the holds are big. After that it's simple, but exposed scrambling.
Take a short length of rope and some slings. You can set up a fairly simple self belay system. Hang sling over spike. Tie one end of rope to it. Estimate how much rope you need to reach next spike and tie onto a bit of rope that length. Climb up to spike. Pull up rope and sling from lower spike. Rinse and continue. It's a reasonable system for protecting short sections.
Edit. Have a look here which has some photos of what to expect.
You should be fine in ordinary boots. I have done it in Koflachs and crampons and although it's supposed to be Winter IV, it's not much harder than in summer.
A good read, thanks for posting it. I can remember a few years ago going up Siabod just after a thaw set in after a winter of heavy snow. It was extremely windy, so walking along the summit ridge wasn't an option. After about half an hour wading through waist deep wet snow below the ridge, I turned back before the summit.