Sorry to hear pigeons got your cabbages, I suppose this time of year there's so little available they spot them a mile off
I've still got cabbages, savoy and sprouts in the garden well frosted - will they grow any more or should I pull them up now? Sprouts a real disappointment as the one plant that produced the sproutlets grew them open rather than tight so they look useless
Leave them where they are unles your have below minus three centigrade for three or four for three days continously .
Most cabbages and sprouts can take several days of hard frost down to about minus 4 but after that they start to get slowly killed off by the cold
You can however saw offf a frozen cabbage and defrost it and sort out any good bits to have that evening /day . The frozen saw off cabbage can be allowd to defrost in a garage over a day or so but it will need eating once it has defrosted.
I'd also leave the sprout plants alone , break off and eat the bolted sprouts as boiled cabbage or use them in soups or as bubble squeak with a bit of pepper & butter on them etc. ... take them from the bottom up to the first set of smaller sprouts you see that are tight formed.
Then see if you get any new tighter sprouts forming up by the tops in a few weeks time.
If it's still bolted sprouts , you can still leave the plants in situation because the tops can be eaten as greens in late Feb /early March when little else is available & the stalks fed to chickens etc. .
Then you can try your hand at making walking sticks out of the sprout stalks if they are long enough ...just like the Victorians did.