Had they summited NEWS theres a bolted rappel. The old descent route went the way they were going down. Its possible they tried to rap off ancient webbing and pitons from before the bolts were installed.

They were rappelling in a snowy couloir on a winter scramble route. A piton pulled and the shock load ripped what meager protection they had for an anchor. Its possible they didn’t have rock pro at all.

In Yosemite it is illegal to use power tools so all those bolts were drilled by hand by hitting a masonry drill bit with a hammer and twisting.

https://youtu.be/oRLmc6Gd628