I'm no artist but my vote goes towards the mascot being some sort of alien (or maybe astronaut?) with a gun. the gun to match the karabin source of the name, the alien to match the "kbinauts" moniker.
So I just stumbled upon one of ernest's comments about it. Yes, the polish instance is a play on words referencing a rifle. however it seems the original "kbin" name actually stems from unix's "sbin".
I guess in the end it ends up being a double reference?