Maybe I was not far off. My wife just arrived back and it seems they were trying to fix the issue on the phone for ages and there seems to have been some language issue in understanding the fix. Then they heard they were looking for 8 volunteers to be bumped and the checkin staff dealing with my wife says to his colleague he has 2 here with visa problems. He gave up trying to fix the issue after that.

I understand many on this forum are protective of the airlines and staff given the difficulties they face but we should try and remain objective. They are human with good ones and bad ones and some may do what I suggest above saving them effort with bumping 2 extra passengers off the aircraft and doing their airline a financial favour. Not saying its a tacit airline policy to pretend passengers are involuntary denied boarding due to visa errors to avoid overselling compensation. But some airlines have done and are doing similarly unethical things to avoid paying compensation. So I wouldn't class it as a conspiracy theory.