Typically, when the time is very very far away from the synchronized NTP
time, NTP is unable to change the time.  So while NTP might be synchronized
with a NTP server, it is unable to force the time in a gradual way.
This is often the case where the system time is in the future.
An administrator usually has to force the discontinuous time jump.

So, it seems entirely reasonable that the time should be able to be set while
in NTP mode.