According to this rule, if the pot was 25k or more, then the ruling was correct. But it appears it wasn't.
I had always thought that simply throwing in an oversized chip when facing a bet is always a call, never a raise. I thought the oversized chip can only be bet at full value if you either state it ("25k") or if there's no bet yet, and you're throwing it in as the first bet (and the pot is smaller than the chip value).
They would not reverse the ruling. He was force to "call" 25k, and lost the hand.
WSOP Main Event players start with 60k in chips.
This was the first year the green 25k chips were introduced at the beginning of the event. They should have made it VERY CLEAR to all players what constitutes a 25k bet with them.