It is appropriate to inform him to turn around.
Sources: There was a place to say that there is no need to warn him because rapes are generally a blessing even when they are behind priests, and there is a small discussion as rape, not in the case of complete rape, according to the end of RA and Okh Tachah 24 Degbi Ketan was condemned as rape, but here even without it there is room to say that it is not in their eyes complete rape), but it seems that the Ketan should be warned about this, one reason since he would come to do the same even in his greatness, as brought by the Ritba 217 in Rish Sukkah, and in particular according to the Haredim who brought The Bahl Rish C. denied that there is a mitzvah in hearing the blessing, and yet there is also an unethical way of educating the miserach when he is great, and even if there is a blessing in it without a mitzvah, it is appropriate to educate him so that he does not get used to losing the blessing in his greatness.
And I will just point out a clear source for the fact that a small is a blessing at all, even when it is behind the priests, even though it is remembered that they are the subject of amen in the Bahchan that is all priests [takh kaha], and it is explained there in the NKJV that they are a קקק in the general blessing, but it is not mentioned there that they are a blessing at all when they are Behind the priests, and rather, it means that from the language of the present they are against the priests, from what they had difficulty with, why should I say that they bless their brothers in the fields and not say that they bless the women and children, meaning that women and children are there in the place of prayer and are not at all behind the priests like their brothers in the fields, so it was made difficult for them that the blessing should be preferred Be unique to those who are there.
מק"ט התשובה הוא: 4214 והקישור הישיר של התשובה הוא: shchiche.com/4214
