There's a cost to open-sourcing code. It takes effort. You must write documentation and clean up your code in many ways. It's good to "clean up code" of course but is that the most urgent thing on your task-list?

Who should pay for that effort? The original author? Yes if they think it's worth it and they can afford to spend the time on it.

There's also a risk whenever you publish source-code, someone might sue you for copyright infringement, or patent violation, etc.

I agree. Nobody owes anyone anything!

I was merely pointing out that it's a shame that

(1) it has apparently been abandoned for years,

(2) people are not able to do anything about that.

(Bus factor == 1, etc.)

Based on the other comments in the thread, I'm sure there are people who would love to contribute.

(Worth pointing out that making something open source isn't zero-maintenance by any means, especially since GitHub still doesn't let you disable pull requests...)