In a recent game my opponent questioned if the empire special character Kurt Helborg is stubborn after his unit of Reiksguard knights is wiped out.

Here's why direct from the empire army look

Specail Rules
The Emperors Chosen: fluffy blurb bit. Any unit of Reiksguard Knights led by Kurt Helborg is Stubborn as well as immune to psychology.

My opponent believes that after the unit is wiped out and only Kurt is left he is no longer stubborn as only the unit was.

If this was the case would ITP also be lost?