moish- just saw your question. What am I, the local posek hador? I don’t have the answer, although I’m sure Joseph, Itzik, yashrus, noitallmr etc. have the right response.
What I do know is: if you see someone doing something wrong, and you know for sure that they will not listen to you if you tell them it’s wrong, it’s better that they don’t know at all; that they at least do the aveirah b’shoigeg.
But- this does not give anyone the excuse not to learn halacha because “it’s better not to know at all”. Hopefully knowledge will come to awareness which will come to doing the right action