I'm pretty sure what you're trying to do is not allowed under Section 1.3 of the AWS Promo Credit agreement. Personally, I would be wary accepting "free" credit that I may end up being on the hook for.
Steam has a similar stipulation - and a lot of people are pissed about it. Basically you can't buy or sell steam accounts - and if you are caught Valve will suspend the account. I personally think it's completely stupid and if actually challenged would not hold up in court (I think the first sale doctrine fits perfectly because if you sell your steam account then the games are no longer accessible to you). But again - I get why, they don't want to put up with scammers or stupid people who try to sell an account and disappear before they send the credentials.
Seems pretty clear to me...
He's giving it away, no money changing hands.
> or otherwise transfer Promotional credit
Is what he has "promotional" credit? He says he has credit... is there a difference? If there is, then that quote doesn't apply. If they are the same thing, and it's used on his account?
If there is no "sale" or "transfer", then yes... it is clear: He's fine to use it as he wishes.
This is very very likely promotional credit. They hand it out like candy.
Edit: Okay, I can see that if his approach is to use it on his own account, but for someone else's purposes, then it's probably fine. I don't think they even have any system to transfer AWS credits
Edit2: Then again I would be wary of publicly announcing that I'm actively trying to use my AWS credits for other people even though I'm not technically "transferring" them...