I don't understand the immediate concern about using 32 bits for file creation and modification times. Its reasonable to assume that if the value has overflown

I don't understand the immediate concern about using 32 bits for file creation and modification times. Its reasonable to assume that if the value has overflown and is very low that its not indicating a date from 1970. There is probably room to add a single bit indicating if the epoch is 1970 or 2038.