This one threw me for a loop. After some research, I think this likely began life as some kind of a typo-like mistake (perhaps indeed on the term locum tenens when brought in from the cited source. I found strong hints they got work for a time answering emergency medical CB and/or UHF radio calls in some area of the outback (keeping in mind this was 1979, long before most folks had mobile phones). Hopefully cleaned up at least a bit.