I hope you are right.
I am speculating here, but I am not so sure.
Depending on how that transfer was structured, the IRS could come back and say that the Simon's were attempting to avoid paying estate taxes by transferring Mel's share to Herb, especially if the IRS decides that the transfer was for less than what would have been fair market value at the time of the transaction.
If the transfer happened after Mel was in poor health, the IRS could come back and say that the difference between what Herb paid, if anything, and the actual market value of Mel's share at the time of the transaction would have been subject to whatever Gift Tax was in effect at the time of the transaction.
The IRS can be very sticky about Estate and Gift taxes. Historically, they are amongst the highest percentage taxes that are ever collected, even though they are significantly less at this point than they have been in a very long time, but Mel's estate likely still is liable for them in general, whether his share of the Pacers is directly involved or not. As a result, I beleive that the IRS will look for every penny it can get and will investigate thoroughly, including transactions that occurred after Mel's health declined.