I don’t disagree that luggage can be a personal item. BUT this will be a problem for nearly ANY item when a group insists on getting a tangible gift! Unless you are quite certain that a person needs/wants an item or definitely shops at a certain store to buy a gift card, you’re taking a chance!
I guess make it an AWAY gift certificate! 
Also the suggestion was not for a main piece of luggage but perhaps an alternative piece - like an overnighter or weekend bag.
Final comment - if an employee is retiring and you really don’t know much personal about them to come up with a gift - you probably shouldn’t even be considering buying a tangible gift! As a whole I think “we” are too focused on things and we OVER gift…