I am guessing his private method includes buying it from another person and that person probably carded or obtain it through a fraudulent activity. But since he is just buying it off another person and reselling it, he states he did not obtain it through card or blackhat but it doesn't include the original person he obtained it from.  The requirement of making us use it within 10 minutes and warning us he is not responsible for whatever happens to the account is just raising more red flags. You can use the gc in 10 minutes and the code will work for sure, but amazon can still cancel the order before it ships and ban your account. If you make a new account it will just flag you quicker. If you use your main account, it will just put it at risk of getting banned.