How can you tamper with a witness who hasn't been identified as a witness ... in a lawsuit that hasn't (yet) been filed?
Call it pro-active witness tampering, then... it’s pretty obvious to all that a lawsuit is coming.
There is legal/technical witness tampering and there is de facto witness tampering. Lawyers have been retained. Motions have already been made [the lawyers asked a judge to order the airline to preserve all records]. Unless United settles out of court, it will go to trial. If it does, the passengers will be witnesses.
Given these facts, United is blatantly currying favor with potential future witnesses. It may backfire, though. Dao’s lawyers may use United’s actions to argue against them.