This is a great question, thanks for asking it. There is not currently a way to conditionally enable/disable drill based on a condition like number of records.
Product Manager, Tableau
Thanks Amy. I was thinking that if we drilled down(link) to another sheet, Maybe we can put a context filter to hide when the number of the clients are less than N (5) .
Your input is very helpful and do you think Tableau may have this feature in the near future?