A United first officer was flying in the jump seat of a Southwest cockpit and he noticed the Southwest first officer doing something wrong (using the speed brake without flaps). She recommended that the first officer deploy the flaps. The Southwest pilot then noticed it and told his first officer to add power, cut the speed brake, and deploy the flaps, and then both pilots thanked the United first officer for saying something.
But after the flight, the United pilot called the FAA hotline to file an incident report, which got the Southwest crew in trouble with the FAA. So now the Unions are involved and Southwest pilots are saying that they won't allow United pilots in their cockpit jump seats anymore.
Seems to me that the United pilot should have left it alone. She pointed out the issue and it was corrected. It seems to me that he was out of line for filing a report on it. But maybe some of the pilots here have a different perspective.