It ain't my problem but I doubt the IRS will leave interpretations like that open. Like I said their wording is crap. I presume it's going to be tuned.
If they wanted to make it ambiguous they would have said "on the day of receipt." Instead, they were pretty clear:
You have received the cryptocurrency when you can transfer, sell, exchange, or otherwise dispose of it, which is generally the date and time the airdrop is recorded on the distributed ledger.
A fork must be recorded on the distributed ledger
before markets can determine fair value. That's just a fact. Arguing taxpayers are supposed to use some price from the future as taxable basis basically means
the IRS didn't mean what they wrote. That's unlikely since the IRS strives to never violate its own sub-regulatory guidance.
The fact that they specified "date and time" is very good for supporters of the $0 fair market value argument.
According to the National Law Review:
In this regard, the IRS stated that cryptocurrency received in a transaction facilitated by a cryptocurrency exchange, is valued as the amount that is recorded by the cryptocurrency exchange for that transaction in U.S. dollars.[10] However, if the cryptocurrency was received in a peer-to-peer transaction or some other type of transaction that did not involve a cryptocurrency exchange, the fair market value of the cryptocurrency is determined as of the date and time the transaction is recorded on the applicable distributed ledger, or would have been recorded on the ledger if it had been an on-chain transaction. As evidence of fair market value the IRS will accept the value as determined by a cryptocurrency or blockchain explorer that analyzes worldwide indices of a cryptocurrency and calculates the value of the cryptocurrency at an exact date and time.
The people who really are in trouble are those who received exchange-issued "airdrops" after the fact and didn't report any income. They are doubly screwed because the exchanges have their KYC.