The regs seem to be aimed at preventing continuous contact and the resultant injuries. The CRC actually suggests using some sort of potholder to protect hands from the metal. The CRC also points out that efforts should be made to prevent trapping the cryogen. When trapped against the skin, LN2 will cause injury since the contact is no longer momentary and becomes continuous contact. For those who suggest sandals as appropriate should think about the possibility that with a major spill, some LN2 could be trapped beneath the foot or under the strap of a sandal, possibly causing injury.
Appropriate shoes can protect the foot for short periods.
If the footwear is frozen, generally it can be removed before injury occurs. The problem I have with faculty and staff is the use of latex gloves while using LN2. The Leidenfrost effect can definitely cause injury if the latex freezes against the skin. The whole idea is to make sure that most any cryogen does not get trapped against the skin. If you can handle LN2 safely without protection, or have done it for years without incident, more power to you.