[asaph]

It seems to me that forks are treated more like RSUs (restricted stock units) than stock options. When a company grants you RSUs, you're immediately responsible for tax on the value of the shares. If you then hold the stock for any period of time, and later sell at a profit, you'll need to pay tax on that profit too. You get taxed twice.

EDIT: IANAL, IANAA, etc...