Once again thankyou for the question,
I will give a short and then long answer.
No it can't, the ability only grants an increase of +2, it does not grant the Kung Fu skill as well
Zui using his ability, boots a saloon to give a dude +2 Kung Fu, This only grants an increase in an already existing keyword and NOT giving that dude the keyword. This is much like the ruling on Sanatorium. This however does not mean that the ability cannot be used, just that it will have no effect on the targeted dude. There are niche cases where you would want this to happen.