Unless this was BYOD, you know that icon that is labeled “My Computer”? Guess what? It isnt yours. Symantec wasnt necessarily the problem here.
Did you have local admin or did someone install the tools for you? Either one should have probably required someone somewhere to sign off. Maybe the problem was process failure or poor interdepartment communcations?
Was there some kind of exception process that you completed to get these tools installed? If so then the fact that they didnt get added to the exception case config for Symantc for your machine shows a process or communications failure.
As per @ronaldpottol comment later, that does nothing in regards to Extended Validation.
Ultimately as Cory hinted, this is a very old problem known about since the first commercial CAs. Let’s Encrypt does not solve this problem at all and I’ve never understood that the purpose of Let’s Encrypt was to solve the problem of “does this server really belong to who it claims to belong to?”.
