One possibility is that when the pilot confirmed to himself that the brake lever was fully home, the pax took that as an indication of "You can hold onto this."
Megan, as I recall on the S-76B with the PT-6, we could only start one engine and keep at idle with the brake on. But as you say, John Dixson or Nick Lappos could tell us the tales of woe with testing these things at higher settings or both engines on.