Tupou remained on the field after his high hit in the second half, as the Sydney Roosters fell just short of an Anzac Day comeback against the Dragons.
The incident infuriated Dragons coach Anthony Griffin, who claimed that the Roosters flyer would have got "two years in jail for that" in Magic Round last year.
With the Dragons fighting to come out of their own end, Ravalawa made a rare second-half break when Tupou collected him around the head.
Referee Adam Gee could be heard saying "it is not as bad as it looked" on the field, but Griffin firmly disagreed.
"He had 30 metres to decide where to tackle him. It was direct contact with the head," Griffin said.
"I don't understand the rules. At least (should have been put) in the bin.
"He would have got two years in jail for that in Magic Round last year.
"I'm not here to bag anyone or make that the story of the night. But it's just black and white. It's not even a question."
Griffin's Dragons were among the hardest hit out of last year's Magic Round crackdown, with a player sin-binned and sent off in the opening 13 minutes.
He also had issue with the fact Jared Waerea-Hargreaves was not penalised for an awkward tackle on Jaydn Su'A, which left the Dragons forward injured.
"I feel for the players and coaches," Griffin said.
"If you're not going to put that (Tupou tackle) in the bin for some of the things that have been in the bin over the last four or five weeks, I don't know where we go now."
Roosters coach Trent Robinson did not want to comment when asked post-match, but Abdo made clear his thoughts on radio.
"From where I was sitting, to me it was a sin-bin," Abdo told 2GB.
"Direct contact on the head. We'll see what the review comes up with tomorrow.
"I was very surprised it wasn't sin-binned I think it should have been."
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