I do not think SEW247 is suggesting he claim the cost of full fare and travel on a cheaper ticket, pocketing the difference. That is clearly fraud, and is not going on here.
The problems of short-notice changes to travel plans has already been covered.
Overall, if this is a one-off, just go along with it. If it is a regular thing, perhaps discuss with your boss once you are established in your post whether you can try to get a better travel experience without costing the company more money.
If I was going to be travelling that route a lot in full Y as most of my long haul travel, I would consider crediting to AA to achieve EP status, get the 8 systemwide upgrades, and start using them (and miles and copay, perhaps) to upgrade myself to business on AA. Only if you can get the ticket issued by AA, though.