There is no package for the JustDecompile on Chocolatey. I suppose you have found the package for the Telerik Control Panel, which is obviously outdated. As far as I know, there is no plans of generating newer version of it.
As of your idea for creating a chocolatey package for JustDecompile, what you can do is to go to our UserVoice portal
and vote for the existing idea for creating chocolatey package
. By doing that you increase its priority on our list.
Telerik by Progress
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items