It's not a scam, because the site owner isn't getting the BTC, it's going to the person/pool who mines the next block.
the btc is in *a* account that the website owner has control of, this is how they are able to give btc out, if they were not in control of it they would have no way of giving the btc out at all. their website keeps track of how much btc is owed and to who. so if a account goes inactive for 6 months they can just take the BTC because the person that 'owns' it isn't likely to come back for it. and if they do, they have plenty of other BTC sitting there that they can give them.
Sorry, I should have said the BTC paid as the transaction fee isn't kept by the site owner. I highly doubt he's taking the .01 and only paying .0005