Utensils

Question

1. As a Jew I am not permitted to use non-kosher utensils to prepare a meal, even if the utensils have not been used for 24 hours. So how come if my friend is going to prepare a kosher meal for me with his non-kosher utensils and I know about this ahead of time, I don't have to stop him and give him kosher utensils. Since he hasn't yet cooked it, isn't it a lekhathila situation, and I thought that only be-diavad we say that food prepared in non-kosher utensils can be eaten (because of setam kelim einam benei yomam)? 2. I asked an kashrut administrator at the largest hashgacha why they insist that you can't eat factory produced foods on Pesah unless the factory's utensils have been kashered before the holiday. After all, there is a halakhah that says setam kelim einam bene yomam and once the food is produced and in the stores, it is bediavad and according to the halakhah can be eaten. He replied that this is a kula and we don't rely on it. When I replied, that this is not a kula but a halakhah in the Shulhan Arukh, he insisted nevertheless that it was a kula in the Shulhan Arukh, not to be relied upon unless absolutely necessary. I know this isn't technically baal tosif, but how can rabbis tell us that explicit halakhot in the Shulhan Arukh don't apply anyomre. Isn't this what the Conservative rabbis do?