I had originally uninstalled Bluestacks using the prescribed methods. And those are the methods that you find when searching.
The issue that I have is that there are some orphaned launchd or other scripts that the typical user would not be aware of. The reason I am aware is because of LittleSnitch reports "some items tried to connect to the internet during bootup before LittleSnitch was fully in control", or something like that. Then the rules can be viewed, but the scripts cannot be found.
Since the rules were marked in LittleSnitch as invalid, I decide to remove them. Now when booting, I do not see the LittleSnitch warnings anymore.
My conclusion is that in fact there were probably no orphans. Just orphaned LittleSnitch rules that were no longer valid. The only mystery is why LittleSnitch reported with the warning as it did, as that now seems to be an invalid warning, or at best poorly worded. Unfortunately I don't have the exact text of that warning. If I did, I might report the poorly worded warning to the LittleSnitch folks.