I think that many airlines require pilots to pass through an in house medical examination prior to application acceptance or rejection.
What might be unusal here is that the airline in question seems to be insisting that recurrent medicals be undertaken at its own facility. This could give rise to pilots being dumped for all sorts of non medical reasons, from the political to the nepotistic, with very little right of appeal if a company doctor has said that you are not up to the standard required.
If, for example, many of the pilots are ex Korean air force, civilian pilots, in general, would be unlikely to be up to the physical fitness levels of an recent air force officer and so could be dumped from the airline for that reason, evem though he would be perfectly acceptable for the issue of a civil medical.
The system could allow for abuse and control and the implication is that this is what is happening.