Maybe you need to stop trying to find the exact wording and use a little common sense in what the ruling actually means.
For one a simulated runner is not going to be a simulated runner very long. The reason the definition of a runner is in place to give the defense an opportunity to reasonably hit that person who might be carrying out a fake or is thought to have the ball because of a fake handoff. So the opportunity to tackle this person is very brief if not so short that you would be called for all kinds of foul if you just hit them by rule
(before this new rule I might add). A quarterback in an option scheme for example would no longer be a runner or even a simulated runner at that point. Now can you do whatever you want as a defense? Of course not. A defender could still be responsible for other illegal personal contact rules that applied before this rule was in place. So instead of this being a "Horse collar” foul, the action just turns into a PF because the same act is deemed dangerous. BTW, the NF did not take this position at all. They would by rule allow you do this act and not be responsible for anything, the IHSA wanted the action outlawed (not the definition, the action) The same the ruling you show does not apply to a runner that was grabbed by the collar (from behind or the side) and now fumbles the ball. Are they are runner if you fumble or lose control of the ball? Of course not.
Also Illini_ref asked a Rules Interpreter directly (which any of us can do) what the ruling is on a situation that was not listed earlier. Just like multiple rules that have gray areas or unclear interpretations from the NF or the IHSA. He contacted Bill Laude and/or Dave Gannaway directly. Not only is this what the IHSA tells us to do, they talk about this a lot on the website and at rules meetings or on the rules video. And since the intent of the rule was to consider the act illegal, the only thing that you seem to be hung up on like many is what the penalty is called. The same act is illegal according to the IHSA; they are just saying that it is not a “horse collar” because that was not the intent of the rule. Maybe that is hard for you to wrap your mind around, but it sound rather easy to me. This was exactly what was clarified at the two live rules meetings I attended and people asked all kinds of questions about an action that I have yet to see this once by any standard (and not matter what you call the foul).
And if you do not like what I have to say, the contact information of these two people is readily available and you can ask them yourself. I am just sharing what I know and I did not make the ruling or the interpretation. But I can tell you from contacting IHSA people in the past, and asking this of National Federation people, the NF takes the position that interpretations are supposed to come from state associations primarily, not always form them. The NF posts interpretations, but states can take those interpretations further and they not only realize this, it is encouraged. Also, every year a new rule that has holes in the rule; states take all kinds of positions. I know an official from South Carolina that also has a license in Illinois and according to him, South Carolina took a similar stance that the IHSA did on this issue, mainly because the two heads of those states that sit on rules committees, were the authors of the horse-collar rule.
I tend to not rely on what people say here for any ruling when I want clarification. Now maybe the website you have does not show the contact information, but if you still need it, send me and email and I will pass it along to you. No website or interpretation is going to answer every possible question or concern and if that is what you or I are looking for. It is not the case because that has never been the function of these interpretations. You have to get clarification if you have it from the right people. And the sad part is they say that so many times in their literature I’m amazed people do not take advantage of this on a regular basis. The reason Illini_Ref asked these individuals in the first place, because we could not come to a consensus on another board discussing this very issue. He told us what he found out, if you do not believe him, contact those people yourself and report what they tell you here.
Peace