As I read the rules, it looks like this applies to an immovable obstruction (2019 rule #16) or a "No Play Zone." (2019 Rule #17.1e) That was also a new term to me, but I think it's an area where you are not allowed to play. You must take relief. I know The Crossings has environmentally sensitive areas that you are not allowed to play out of. And I have played other courses where flowers were considered a No Play Zone or Ground Under Repair.
I could have taken more relief (two club-lengths), but I didn't. So I believe that since I could have played from the hazard, I was allowed to take relief with my stance in the hazard. In fact, I believe that once my ball came to rest in the relief area (area #3 below), the ball was live, and I had to play it from that spot.