"what would happen if he says nothing? Has anyone ever heard of the IRS actually catching this and dinging the taxpayer?"

Whew; I'd whistle if I could. Imagine what happens some 20 years later, because they pay the excess tax (and penalties) for every year it was not removed, and until it is removed, and the earnings are taxable when removed.

They don't need to live with it for the rest of their lives, if they Remove the excess now. Right now, in fact, with the market down, depending on how that was invested, there may be little to no earnings or even a loss (not claimable, of course). Do it while it hurts the least 🙂