If asked to remove a face-covering for identification purposes (as allowed in the regulations), presumably one should sanitize first (having potentially touched a potentially infected surface (table, ticket machine, gateline etc) in order to prevent contaminating your face covering, lower covering as requested, replace covering to continue, then sanitize again in case your covering was already infected and you have now transferred it to your hands and thus on to any surface about to be touched!
Indeed - although I'm not sure how often people would be expected to remove theirs for identification.