I was surprised, too. The 2nd place woman started with a jacket and ended with singlet and arm sleeves.
I would think that's the way to go.
tech shirt, short sleeves, with arm warmers, and maybe half tights, and a running cap is all you needed. Trust me. Yes, cyclists ride in all kinds of weather. So do most runners. But cyclists spend 3 or 4x the $$ on their outfits and do even mention their cycles. I ran in the Hyannis Marathon the year it was ankle deep slush and we ran single file in tire tracks.