I'm not familiar with those creels, however I am familiar with caned chairs.
Unless someone, here, knows for sure....
A gentle washing with a soft brush, mild soapy water and rinse well shouldn't bother the bamboo. I would suppose it gets wet when fishing, anyway. The water may soften the bamboo, as it does with caning. If it softens too much, you might want to stuff the creel with bundled news print to maintain the form/shape of the creel, while drying.
Caned chairs are finished with shellac, usually. Maybe test a small area with a more water resistant finish, should you decide to put a finish on the creel. I have no idea if creels would have a finish on them, or not.
I use Frank's Cane and Rush Supply for my supplies - http://www.franksupply.com /
Maybe inquire of them or a supplier near you, for expert advice specific for bamboo. A good sporting goods outlet may know, also.