Dave, what is the purpose of protecting M. basjoo

To get them taller to be wrecked more by the wind

To get them to flower and then be wrecked by the wind, and once flowering there is no more leaf growth so they just get more and more tatty

I agree with the sentiment Ade has, and that is I want my garden to look good, not just have wrecked plants to put a tic in a box.
I cut my basjoo back once wrecked so in 16 years I've only ever had one flower, but the shorter bananas look far better, as sheltered from the wind. As have been put on other threads, members M basjoo mushed to the ground last winter have reached 2m this summer and in forest proportions. I completely dug a clump out at the end of March, well, not quite all, as 5 pups appeared during May and have reached 6 to 7 feet
By all means protect if you want, but in the -6C we get here they are stem hardy.