I think that a sensi or sempi has every right to make suggestions on how to act outside.
But I disagree that they sould "Tell" Someone how to behave. They should Suggest. "Tell" is too harsh.
On senior student said while teaching a class once to us. You should respect the earth and not pollute it. IF you see someone on throw something on the gorund you can even ask them kindly to not do that.
Anyways this was just a suggestion, not an order. This I beleive is ok, suggetions help alot. But orders are wrong.