Cash playing?

[TacitMike]

I was at foxwoods last night playing 1/2 NL. After about four hours or so of table time, Chris Smith came over and sat at our table since Kimberly Lansing was already playing there. Chris (who is a regular 25/50 - 100/200 NL player) said he got drunk at dinner and just wanted to play around at 1/2 for the evening, so he sat down and bought in for the maximum (of course) which was 300.

He got stacked twice which is sort of funny, but he was laughing most of the time since the buyins here are typically a preflop raise at his regular game. Anyhow, after he busted one time, he pulled out $400 from his wallet and was getting ready to buy back. I pointed out to him that the max buyin was 300, so he got 300 in chips and left the last 100 sitting behind his stack on the table [this is mistake number one]. Non foxwoods regulars should note that 100s on the table play under normal circumstances.

About half an hour went by, the dealers had rotated, and Chris was involved in a pot with a guy at our table who had turned the nut straight. Chris pushed the kid all in, and of course he called and chris was drawing dead. Chris pushed his chips towards the kid, and I sort of bit my tongue as I saw the $100 sitting there on the table. Eventually a few others at the table noticed what was happening and started wondering whether or not the kid who won the pot was entitled to the $100 that chris had, but should have never been allowed to put on the table in the first place. Since the dealer at the table now was not the same dealer who cashed the previous buyin, she had no way of knowing what the problem was.

Of course, Chris just shipped the $100 over because he realized it was his fault, plus I think it was mostly a waste of his time to argue over pennies. Fully understanding that the problem could have been avoided by the $100 not being put on the table in the first place, what is the correct decision?