By definition, it the client Alice gives contractor Mallory access to user account alice, that's worse than giving them an account called mallory.
Accounts are basically free. Not having accounts; that's expensive.
Accounts are basically free. Not having accounts; that's expensive.
Let's assume they need access to the full service account environment for the work, which means they need to login or run commands as the service account.
This is a bit outside my domain, so this is a genuine question. I've worked on single user and embedded systems where this isn't possible, so I find the "unprofessional" statement very naive.