If they can not master both types of landings I will not sign them out as competent on tail wheel airplanes....period.
That has to make sense - sometimes a 3-pointer is appropriate, sometimes a wheeler. And sometimes one just wants to ring the changes.
It's better for the stude to be taught wheelers and tail-up taxying by their instaructor rather that try to teach themselves to do it.
If you don't have the skill not to nose-over and not to let the aeroplane swap ends in a high speed tail-up taxy you shouldn't be signed up as competant on tailwheel aircraft.