Flight manual of A-1B says absolute ceiling is 16000ft (by extrapolating the climb curves at ISA temperatures from 6000 ft to 10000ft).
Maybe my prior message was not clearly expressed: the A-1A is basically the same aircraft as the A-1B and has all similar performance data except, suspiciously, Vx which is 58MPH at sea level and 60MPH at 10000 ft, likely the correct values for the A-1B give or take a knot.
Another potential explanation besides a typo is that Aviat does not like recommending climbing at that speed and decided to pad some margin on VX, because it is so close to stall speed on that aircraft. An engine failure in a climb at the real VX would result in a nearly instantaneous stall.
I have myself added such margin above the real VX for that particular reason when publishing AFM data of a (quite different) single engine aircraft. If you keep that margin constant, VX ends up crossing VY at some altitude then, apparently violating the laws of physics. That is because it is not the real VX but rather a recommended best angle of climb speed that adds some safety margin above the stall speed. These margins are normally not disclosed by the manufacturers, even upon specific requests.
This is my best guess, I am not familiar with the Husky.