Dand, it isn't practiced that way in SE whatsoever. And I have never heard of anyone being indicted, prosecuted or convicted because he/she claimed residence too soon for subsistence purposes. Therefore, if the law is as you say, and it likely is, no one is aware of it and the law is not effective. The state routinely prosecutes people for claiming Alaska residence illegally but that is a different matter of course.
Here in SE, as soon as someone claims residence in a community that qualifies for subsistence they themselves qualify for subsistence even if the state still requires them to purchase a nonresident license. Moreover, if someone has a Native appearance, especially if they are hunting and fishing with others with Native appearance, they are not checked for licenses by any authority, state or fed. I am one of the many long-time Alaskans who have regularly and routinely witnessed this.
I would be interested in learning how many prosecutions for illegally claiming to reside in an area qualifying for subsistence there have been in your area during the past year and 5 years. My belief is that people who live in Anchorage routinely qualify for subsistence taking so long as they travel with relatives who reside in the so-called rural area. I will be pleased if you can cite evidence that supports the law being enforced.