This is true but it's more of a cya for the next person who may work on it.
From his ignorance only.
Who cares if white wire is grounded or ungrounded in this case. If 120 volt and not marked and is disconnected while energized it can still nail him and he will think it neutral and why did it do that?
My thoughts on marking a white wire where it is allowed to be used as a non grounded conductor has always been that you are only protecting those who do not know any better and even then they still don't have a clue of what is up.
If I see a white wire landed on a fuse or circuit breaker it does not even cross my mind that this could possibly be a neutral.
If in a lighting outlet box I see a white wire connected to one or more black wires I don't give it a second guess that this is not a neutral same at the other end where the switch is.
If I see a white wire connected in a piece of equipment that is typically 240 volt equipment I may check voltage if there is any doubt but otherwise assume and treat it as if not a neutral.