It’s not so much that a contact approach is “prohibited” by OpSpecs as an air carrier would have to be approved to conduct contact approaches. There is an OpSpec, C76, in the FAA list of OpSpecs that allows contact approaches. Whether any air carrier has C76 I don’t know. One of the issues could be training. You would have to find a sim in which you could perform a contact approach. Many airlines don’t do circling approaches in less than VMC conditions because they can’t train for it. I can only recall doing one contact approach in 40 years of this foolishness. Took a Twin Beech into San Antonio one morning. I don’t recall if the ILS was down or what led to doing it but I knew from multiple flights into San Antonio that a certain highway led to the airport. It was about 600 broken and 2 miles as I recall. But I just flew along the highway for a few miles and there was the airport. How you would set up the sim for that I don’t know. And even if you had the graphics for one airport how would you apply that to another totally different airport?