Glad to see this raised as there seemed to be more commentators saying SOD tackle should have been black card and pen than not. Which I don't agree with at all.
If SOD tackle is a black card and pen then every single tackle that is technically a foul in that zone is a black card and pen. That is not what the rule is for. The rule is for the cynical, shameless 'I'm pulling you down so your team can't get a goal' type of tackle. I'm biased but I think Walsh got it right. Maybe moreso by the spirit of the law rather than the letter of the law. SOD is still trying to make a clean tackle when there is a tangle and it's clearly a foul, but there's no intentional cynical element to the foul at all imo.
Hayes had to be a black card and pen due to cynical rugby tackle nature of it and the player is in the red zone. The rule was created to stop defenders using that technique and it seems to be working.