I think that might depend on how long the step parent has been there. If the step parent is doing the raising of the child or not.

My step dad had equal disciplinary reign as my mom did. Because he was my dad. He was raising and supporting me. My sperm donor was not in the picture, but even if he had been, my step father and mom together kept the roof over my head, food in my stomach, clothes on my back, and all other needs, as well as the needs of the dozens of interests and activities I decided to take up.

He was an equal parent to me as my mom, he just didn’t come into my life until I was about 4. But being that equal parent he deserved equal treatment in all aspects, including discipline.

In this particular case, OP said in comments his mom was worse. It could be the step dad was the lesser of the two evils in relaying this message. If that is the case, I’d hate to know what mom would have said.

Also, let me note, I think this situation is insane! I feel for OP and hope they’re in a much better situation now with their father!