The airdrop is akin to a "gift". The IRS tends to hold the gift giver responsible for paying any tax owed. So if Craig Wright forks Bitcoin in such a way that it initially has value upon being airdropped, he will be liable for tax payments to the IRS of the sum of all bitcoins in existence times the price.

Who pays the gift tax? The donor is generally responsible for paying the gift tax.

So it's on him to hope that when he gifts the coins, they are worth zero.