I'm assuming this is sarcasm? Why on God's green earth would you want to dockerize a utility like this?
That aside, it does seem like a very useful utility.
To respond to your edit, I don't think dockerization is necessary for a simple binary. You're not running any thing that could benefit from it. It makes sense if you want to run some kind of network service (torrent client, web server, ftp, smb, blah blah blah) and forward a port to your instance. That way, you can pre-package it on something like unraid. Here, it doesn't, and (as far as I know) even unraid can install a simple binary.
Why wouldn't you want to dockerize it? It has a huge number of potential dependencies (pandoc, pdftotext, etc). Getting all those working on my Unraid storage server for searching is going to be painful.
I feel like this case might be better served by something like flatpak or appimage. While I'm usually not a fan, this is basically exactly what they're built for, as compared to docker, which is not designed with this in mind. I don't want to have to prefix every command with docker stuff.
That aside, it does seem like a very useful utility.
To respond to your edit, I don't think dockerization is necessary for a simple binary. You're not running any thing that could benefit from it. It makes sense if you want to run some kind of network service (torrent client, web server, ftp, smb, blah blah blah) and forward a port to your instance. That way, you can pre-package it on something like unraid. Here, it doesn't, and (as far as I know) even unraid can install a simple binary.