Oh, here is how the Three Years is seen on the worksheet:

The Amount is split into thirds, so only that one-third is part of the year's Taxable Income.

For a $273,000 distribution, he would have $173,000 taxable gross + 1/3 of the $100,000 disaster distribution portion, or $306,000 taxable additional gross income. Next year, he has the additional $33,333. The final year, he has the final third, the $33,333 added to Gross taxable income.