The most important quote from that:
To be recognized as C&R items, 478.11 specifies that firearms must fall within one of the following categories:
a.Firearms which were manufactured at least 50 years prior to the current date, but not including replicas of such firearms;
Those on the list were put there because of specific requests for firearms less than 50 yrs old, or because of confusion over the 50 yr. rule. And they are never removed even if well over 50.