I don't get this unfair advantage theory... Headsets are available to any and everyone... Its a choice - you either choose to have one or you don't...
Hacking is an unfair advantage. Ethics aside, the ability to hack isn't knowledge that can be bought at a store... There are only a select few capable of doing this...
BTW - You can get a quality headset cheaper than the actual cost of a COD game... The Turtle Beach X12 for example - Amazon $44.68