Can one give or sell non-Kemach Yashan products to a Jew? Is this like causing them to sin?
You can’t sell something that isn’t kosher even to a non-Jew, since we are afraid he might sell or give it to a Jew. But chadash has some poskim that permit it. Therefore, if the Jewish customer is ot stringent and eats these foods, it is fine to sell it to him.
RABBI SHAY TAHAN