It has been a few years since I flew in the GOM, but24'x24' is a standard small heliport size. I used to do slingloads to them daily. Radio contact is not required, and not usually available on these platforms, and often not available to large production platforms. It depends on the operator and the operations. For those operated by small contract production companies, radio contact is seldom possible. They don't have enough personnel to do the required work, nevermind monitor the radio. I'm assuming (and I know all the problems with that, but I've been there and done that) that the pilot was told to pick up a passenger at ST67, and the dispatcher assumed the pilot knew that he would be on the drilling rig. It seems the pilot didn't. New pilot, job pressures, lack of information, and a tragic end. That may not be the actual situation, but I would bet some money on it. Putting out a NOTAM would have done no good, since it would have been more than 4 months old, and nobody reads those anyway. They may glance at new ones, but old ones are pretty much ignored. Too much useless information that doesn't apply to the day's work, so it's all ignored. I'm not defending that, I'm just saying it's the way it is. I always considered that I was paid for using my judgment, not for flying, and still do. I would have landed on the rig and made the passenger walk all the way over to its helipad if he was on the platform, but if I were a new guy, no real idea of how things worked, and worked in a rather hostile environment where I was worried about keeping my job, I might have seen things differently. It's clearly pilot error, but morally, the supervisory chain has to take some blame. I'll try to hold my breath until that happens.
Mars, ICAO requirements and procedures may as well not exist in the GOM. That's foreign stuff, and anyone who even suggests that there might be anything worthwhile in any of them would be laughed out of the room. Louisiana is hard-core conservative territory, and they don't approve of anything European, especially Sharia law.
