It's a good counter argument. This kind of touches on something I'd like to see on steemit: the ability to have longer term rewards. A few ways I could see this happen; for example, imagine you could refresh a post in such a way that only new people who didn't vote on the last one could vote on the new one. In a way, that means only the new audience could give you a reward. There's various reasons why this can't work in the steem system, but I digress... it would be interesting.
RE: The Double Spending Problem on Steemit