Always good to show the flag at the big events, even if you're not going to win. With the ignorant slagging you see on the YY forum about how supposedly all Cherubs are held together with duct tape its surely good to get the sorted modern boats (as well as twenty year old ones with duct tape assistance) out on display at every possible opportunity, even if you're not going to win. Easy for me to say though: I'm not proposing to get my 20 year old Canoe out!
And in the case of the Bloody Mary, it helps everyone if people who find they aren't going to be at the top end of the fleet retire early: it saves congestion on the beach and in changing rooms. So its good manners to do half an hour or so and pack up if its cold and boring, and you still give the class some exposure.
In some ways the weather forecast doesn't look as bad as the year Flat Stanley won: that year the windchill was so extreme and the water so cold that virtually every system of the boat was frozen solid with spray when they finished. The boat was virtually underiggable (is that a word? Is now!): Guy had to get a bucket of hot water to tip over the kicker tackle, which was one solid block of ice, before they could get the main off!