Now all that's needed for a "fair distribution" is a post-announced cap on the amount allowed to invest per address. Since this was not announced previously, chances are excellent that not too many investors used multiple addresses in the pre-sale.

I'd propose to use the median value of about 0,5 BTC as the maximum amount for all investors, which would still result in around ~160 BTC total. This would mean that the developer would  have 450 BTC less than without the cap, but this would be a very strong sign that he is interested in a fair distribution. Any accusations that he himself is the top investor with 75BTC (12.29%) would also no longer make sense.