allow bitcoin users to claim a share of any pre-mine in direct proportion to the percentage of bitcoins market cap they control.
If you are a bitcoin user, you can use your bitcoin private keys to claim a percentage of æther exactly equal to the percentage of the bitcoin market cap you controlled at the time of nucleus creation.
If I understood correctly, the more bitcoins you have, the more premine you'll get. In other words, the richs will get richer and Satoshi Nakamoto will get the lion's share of any altcoin premine.
Surely you had something else in mind, didn't you?