It has a ticket!
This isn’t a story of an inconsiderate plane passenger. In fact, the very reason why this was posted is because of one huge misunderstanding. Apparently, a flight attendant warned the cello’s owner that they should’ve checked the musical instrument in. There was no way it could fit in an overhead bin, and it wasn’t going to take someone’s seat.
That’s when the owner pulled out the boarding pass for the cello. The instrument wasn’t going anywhere, and it would like a coke with ice. Musical instruments don’t get treated with the respect they deserve in cargo. It’s better to get them a plane ticket than risk them coming back to you in splinters.