Should elephants have legal personhood? An upcoming case will decide
theatlantic.com
theatlantic.com
The publicized examples involve money.
Furthermore, it doesn't seem like the article mentions guardianship at all. In fact as it stands it would seem that elephants in general already have guardians - whomever can assert a property right over them. The question is whether an elephant itself should be recognized as having its own perspective. In this way, this case would seem to be more about reforming the current guardianship of elephants to increase their agency, rather than reducing it as you're making out.
And yeah to your general point, the courts are imperfect and seemingly terrible when we look at their worst abuses. But that seems somewhat orthogonal to the current question. If we get to the point where say some billionaires are abusing the ability to legally represent an elephant (to further their own interests while harming that elephant), then we can focus on that specific injustice.
If we give elephants sub-human agency; do other animals get it too? Are they still "property"? do some humans become less than human? There's non-small questions here that can be re-examined and debated; but I fear there's going to be just a slide into a new ethics without ever evaluating the merits of either the old or new.
I think charismatic megafauna might benefit even more from this effect.
I suspect that this would change the calculus of the likelihood that a bad actor would be the representative of elephant-persons. While bad actors would likely be attracted to the role, I think there'd be greatly increased scrutiny of both the selection process and the role's activities due to elephantine charisma and the uniqueness of the situation.