Dean stated making a big deal out of this would be making a mountain out of a molehill. I think that's very subjective to the buyer. I don't think the seller or broker get a say about that.
If I were the buyer, I'd think it was a mountain.
I thought a little while about why this would upset me so much if I were the buyer. Spending so much on a luxury purchase, I think it's important to get a good deal, or a deal that you're comfortable with the outcome.
If I were the buyer and this was sprung on me at the last minute, it would be very difficult for me to avoid the conclusion that I was snookered. And I do believe that that would taint my enjoyment of the purchase.
The analogy that I keep thinking about is if an owner waited until after closing to disclose that a murder had happened in the house you just bought. You might indeed have still gotten the same deal you originally bargained to get but to suggest that there's no harm as a result misses the point. There's a reason why such things must be disclosed up front, and there would be unfair advantage to the seller for failing to disclose, an advantage that couldn't be dismissed as accidental, whether it was or not.
I think that's a fair analogy because in both cases, for me at least, such a disclosure would taint my enjoyment of the purchase to the breaking point.