Thanks to Lacerte.

Someone at Lacerte heard what I was saying. While working on a Form 706, Line 9a Basic Exclusion Amount was changed from the incorrect amount to the correct amount.

Now, you cannot start working on a Form 706 without entering the date of death. That date of death is used by the program to look up the correct exclusion amount for the year of death and input that into line 9a. While still hard entered, it is the correct exclusion amount. You can see for yourself by creating test Forms 706 with different dates of death and see the correct exclusion amount for that year appear in line 9a.

This is so much better than the solution I was originally told to do- prepare the return by hand.