I'm quite sure that very many rebuilds/updated carbines were included in the sale. With very few exceptions, they had been used in WWII, updated/rebuilt, then used in Korea, possibly being redone again. These were simply carbines from long-term storage that were deemed 'surplus'. The use of the term 'unserviceable' was simply a means by which to surplus-out the carbines while satisfying the 'bean-counters'. They definitely were 'serviceable' in every respect. The same term was used to surplus-out thousands of U.S. pistols during the same period, some of which had never even been issued (the perfect late Remington Rands for example), along with the majority which were rebuilds.
So the term 'unserviceable' on these invoices has no meaning in the technical sense relative to suitability for use.