Let's be clear.
The charging document (the criminal complaint) states
"Initially, he did not exhibit any bizarre behavior. [During climb-out from JFK], Osbon said something to the FO about being evaluated by someone; the FO was not sure what Osbon meant. Osbon talked about his church, and needing to "focus". Osbon asked the FO to take the controls and work the radios. Osbon began talking about religion, but his statements were not coherent...... Osbon yelled over the radio at air traffic control and instructed them to be quiet.
Nothing in that document indicates there was unusual behavior while the aircraft was at the gate, or prior to take-off.