Klein sent Ponga packing during the second half of the opening match in Sydney, deeming his tackle on NSW winger Tolu Koula was a shoulder charge with direct contact to the head.
The controversy around the decision was further inflamed post-match when the match review committee charge sheet only cited Ponga with a grade-two shoulder charge, allowing him to escape with a fine.
A grade-three shoulder charge would have wiped him out of Origin II with a three-week ban.
But the NRL supported the match-altering call by Klein, which allowed the Blues to turn a 20-6 deficit into a 22-20 victory.
"The NRL supports Ashley Klein's decision to send off Kalyn Ponga during State of Origin Game One," NRL GM of elite competitions Graham Annesley said in a statement on Thursday.
"This incident involved clear and forceful shoulder-to-head and head-to head contact with no mitigating factors.
"Player safety is extremely important and the game will make no apology for taking strong action on foul play."
According to the NRL, bunker official Chris Butler told Klein it was "at least a sin-bin" but under the laws of the game the match referee had the final say on foul play.
Annesley explained a change to the judiciary code in 2022 meant incidents during representative matches were treated differently, which is why Ponga avoided a two-game ban - the outcome for a grade-two charge in a regular NRL game.
"This was to ensure clubs were not penalised for players' actions during representative matches," he said.
"The judiciary reforms are designed to directly penalise the player responsible for foul play during State of Origin, rather than their NRL club."
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