Waheguru ji .. I believe intentionally doing the beadbi of kesh is against sikhi.. so anything which is not intentional is fine.. like even during washing of kesh.. many fall..
Here, we know that using a rubber band can harm our hair.. if we are sure of the texture of our hair and know that we can avoid the beadbi.. we can use that as well..
Please correct me if I am wrong here.
Waheguru ji