The Meaning of Rank

[Spartacus Maximus]

That's why rank should not be taken as a standard definition of skills. If you reach say 3rd dan but do nothing to maintain or increase your skills, eventually your ability will decrease but you will still hold your rank. It takes a lot of determination and effort to keep up skills for as long as possible.

[Hammersmith]

If the student has met the requirements as defined in the curriculum but is lacking in other areas perhaps the answer is to let your sensei know how you feel and that you would like to present a plan to the student outlining what you believe they need to work on to fix up those kinds of things.

Laying out goals and formally setting expectations is never a bad thing. It may be possible that the student in question is not aware that they need to pay more attention to things like etiquette and this is a good way of sending that message loud and clear.