I don't see a problem with this, on the contrary it seems like an excellent idea.

Your fork will have coins pre-distributed so you don't have the problems with early adaptors.

You could even apply some filter that defines which of the older coins are valid.  Or you could exclude all addresses with more than X coins.

Do whatever that maximizes the spread of the coins and minimizes variance.  The initial allocation of coins is one of the major problems that Satoshi had in his papers, and that is the reason for the constant rate given to miners.  However with an existing economy you can utilize the dillution that has already happened to your advantage.

I think this is a superior way of bootstrapping an alt-chain to maximize the economy.