LOL. I've said it before, that only someone with no experience of breastfeeding in their household would have made that stupid rule about the baby being present. If the baby was present there wouldn't be any need for the bottled milk! (OK, some possible exceptions if the kid is a flailer and Mom is concerned with being modest in tight quarters.) News flash: mom produces it, and will continue to do so in the short-term even if the baby is no where in the same time zone. It has to go somewhere, and if there is no baby present, the somewhere it properly goes is to the inside of a bottle.

My suggestion on the proper way to handle the issue is to ask to see the pump. (Not handle it, just see it, case flap open. The horns and tubing give away the purpose pretty clearly.) If the passenger is female and carrying a pump, then she should be allowed to carry the bottles of milk with it. If you really want to be invasive about it, ask for a physician's note that contains the passenger's name, but for criminy's sake, drop the business about the baby being present.

PS: 100 oz. of milk is a little over a day's worth if you produce well. It will keep on ice in a cooler bag for up to 48 hours if the ice is changed constantly and the bag is well insulated. (32-39F) Longer than that and it would need to be hard-frozen and kept frozen. It makes more sense to chill than to freeze for short-duration transport, because once thawed, previously frozen milk must be used within 24 hours.