Earlier quoted context omitted.
We're not talking about someone who "just happens to be within earshot" of something that is inside your private garden and not open to the public. If you put a note on the public noticeboard saying "I have planted some things in this area of the public commons and I am the maintainer them" can you defend the idea that you are not voluntarily offering to maintain something?
Yes.
1. The difference between ‘abandoned’ and ‘maintained’ is that ‘maintained’ is bounded at the lower end to a greater-than-zero amount of maintenance work. Not a specific amount but necessarily >0. (Without that, “maintained” and “abandoned” become the same thing and that’s absurd).
2. “I am the maintainer” can be a voluntary statement, it’s not compelled (e.g. by a gun to the head).
3. The role of ‘maintainer’ is ‘doing that >0 amount of maintenance work’.
?
By the time we’re arguing how much maintenance, you’re agreeing with my position. In the case of your garden, if I saw it on fire I would think it reasonable to contact you about the fire given you are the gardener. I wouldn’t contact someone who was not the gardener.