As far as I’m aware the most recent version of the Uninstall Utility, avastclear.exe, should be backwards compatible. Obviously forward compatibility can’t be guaranteed with an old version of avastclear.exe.
It is still better than a user trying to do this manually if they don’t have the experience/knowledge.
As far as I’m concerned it does sufficient a job to resolve many issues which is seen in the many users that have done this on recommendation in the forums. I also believe it does a better job than the many so called cleanup tools out there.