Miners should be able to easily detect erroneously high fees in the same way they detect transactions with too low a fee and also reject them outright. There is no philosophical argument required.
Nah, then someone else would mine it and possibly keep it. If you know in the end you'll do the right thing you should definitely take it and if they come to you asking for it give it back. As a large mining pool I think this is pretty much expected, otherwise they have a terrible business and I would never use them! That's like a bank accepting a $3000 fee then not refunding it when the customer says they made a mistake.