And thus according to the IRS, those who automatically received this diabolical free airdrop owe income tax at the market value on the free Core tokens airdrop at the time of the said timestamp. The market value will be whatever nosebleed BTC price before Craig starts his posited (and warned) SegWit donations attack
Upon receipt of any forked coin the forked coin is initially valued at zero. You assume that you have been gifted a zero value token. When you finally sell or exchange that token for something of value you then compare the gifted value (zero) with the value of what you receive upon exchange/sale and you then pay capital gains at that time.
It is akin to receiving a baseball card of little to no value as a gift. But then after 10 years that baseball card is now worth $1 million. You must now pay capital gains on $1 million worth of gains. If you hold that baseball card until your dying days, even though it has a lot of value, you would never need to pay any tax on it.