First, I understand the recent court ruling bans the FAA from requiring hobbyists from having to register. And, I understand that the AMA is a private organization with guidelines for it's members and has no legal authority to rule the hobby or overrule the FAA, right?
But in regard to the document you attached, it says nothing about assuming it is safe to fly as a hobbyist below 400' when within the 5 mile radius of an airport tower or other restricted air space. Some things are basic common sense. For example, I may wish to take off and land as a hobbyist 4.5 miles from an airport tower. I plan to fly well below surrounding treeline and other structures. According to the SEC. 336. SPECIAL RULE FOR MODEL AIRCRAFT.
(5) when flown within 5 miles of an airport, the operator of the aircraft provides the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport) with prior notice of the operation (model aircraft operators flying from a permanent location within 5 miles of an airport should establish a mutually-agreed upon operating procedure with the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport)). I would still need to give prior notice and establish a mutually agreed operating procedure with both the airport management AND the ATC tower operator. Not only is this very difficult to get to these people, it is also silly from a practical common sense view. I'm sure the highly intelligent ATC operators would consider me calling them up every day for notification on each flight like a commercial pilot planning to do take off's and landings at the airport as harassment under the guidelines of the FAA rules.
While I agree the 400 ft rule you stated is good common sense it is not in the regulation referenced. Likely no enforcement would be done in my example as an accident with a commercial flying aircraft would be impossible. But, the regulation is there and if they wanted to play a game in court, they could pull that regulation out and use it against you. So if you fail to notify the two people at the airport you wish to do take offs and landings in the restricted airspace but well below structures and treeline, you are illegally flying. I'm not even sure 400 ft would be a problem 4.5 miles away, but a half mile away it surely would be.
I'm not a lawyer, as if that matters, and I'm new to the hobby, just trying to understand how to be safe, legal, and still enjoy the hobby. If it means being illegal but never being in a condition where I will harm anyone, I guess that's how we roll if being honest about it.
I appreciate any correction to what I stated as I'm just trying to make sense of all this. It was complicated before, now nobody seems to know what the rules are and how they apply to me as a hobbyist.