If "Reuven" believes the halacha to be one way and "Shimon" believes it to be more lenient may Reuven rely on Shimon to do something for him based on this leniency or does he have a mitzvah to rebuke Shimon instead?

A practical example: Reuven's Rav has given a psak that not using a kli sheini is bishul m'deoraita. Shimon's Rav holds you can use a kli rishon. Can Reuven drink a tea made for him by Shimon?