You are probably right at every aspect for what you said.
I don't think I'm the only user representing the group of enterprise environment users with the following situation:
1. does not support W10
2. does not allow updating to W10
3. does not push/force installation of .NET Framework 4.6.1
... + 4. loves to use Paint.NET
This causes usability issues for a minor(/major) group of users - considering the .NET Framework isn't pre-installed the Paint.NET can't either be installed as unattended installation. As .NET Frameworks are quite rigid I'd say this would require some sort of compromise. The previously required .NET Framework versions have been, for what I've understood, rather widely built-in in the Windows OS's'.4.6.1. is not. I hope it's not just me hoping to see an up-to-date Paint.NET installer which a] supports <4.6.1 version of .NET Framework or b] includes the .NET Framework's required installation package (*)
(*) = Yup, the package is rather big as MB's (but as a separate installer it doesn't bother the rest of the users). Also I don't actually know if an unattended installation of .NET Framework is possible.
This is just discussion and suggestions, but the real thing is that at the moment I don't know how our environment can support the deployment of Paint.NET done as unattended installation.