I don't even understand why this one is close.
Wife kills Husband. Husband has a 401(k) account. Wife would ordinarily get it since she's the beneficiary, but you can't benefit from killing someone. So the 401(k) goes to Son, a minor.
Does Son have to pay tax on the money?
Of course he does. That's the way these things work. When you get money, you pay taxes on it.
I can barely even understand Son's claim that Wife should be taxes instead. Wife didn't get the money. Son did. That Wife could have gotten the money by not killing Husband, or by potentially claiming that she didn't kill Husband (she pled guilty), is irrelevant, 'cause they didn't happen. Which is why Son got the money, and is precisely why he's taxed.
Easy cases make good law.