Emily,
Carter and I were looking into this in February of last year, and the need arose again, so I brought it up today.
I have been eyeing a remake of this package for a long time for some of my projects. To be clear: there is no fire that needs to be put out, but I do have a need.
It's not a "need" (not a technical one at least), it's a desire to control a certain package name. Even if there was no responsive maintainer, I'd argue that if anything that name should be given to Kowainik who already support the de facto standard Haskell library for dealing with TOML, 'cause their package fits your criteria (I absolutely do not agree with that criteria, but that's irrelevant)
hackage names are a community resource, and they deserve to be thought through carefully
much better than your yet-to-be-written library (despite the fact that you'll most certainly produce a great library). If "Hackage real-estate" is that "precious", as you put it, it shouldn't be given away on the basis of a promise to write a standard library, there should be actual code to compare.
I'm genuinely surprised there was someone else made maintainer of the package without a public takeover. When/how did this happen?
I do not feel like the author of a library takes the responsibility to inform the public about giving someone permissions to their own library by uploading it to Hackage. There should be some package metadata that specifies a way to contact the maintainer, but that issue is now fixed.