It would make more sense to self-answer your existing question with the corrected flowchart than to start a new question solely for the purpose of self-answering.
The virtue of your original question is that its problem — "is this right?" — is fairly narrow. It's also very to-the-point and understandable.
If you really want to fix this question (not just demand it be reopened without having to do anything), then you have to address the reasons why this question was closed and the other wasn't.
The virtue of your first question — narrowness and clarity — is a virtue that your new question doesn't share. It's a borderline question, yes, and maybe if it was borderline in only one way it would be OK to leave open, but it's borderline in several different ways that add up to one big "too many problems to keep open" judgement:
It's broad, but on the borderline: some people will think it's not too broad, other will think it is.
(This is largely what's tripping you up, I think. You don't think it's too broad, and are perplexed why it should be closed just because some people do think it is. If this was the only problem the question had, maybe you'd be right, but there's more.)
It's very, very similar to the last question you asked. A question that's so similar to the last question someone asked is a red flag to vote-to-hold-privilege users that there is a problem. Holding is often the solution for when there's a problem with a question, because that gives the question time to be fixed (before answers start getting submitted and add to the confusion). And in the case that it can't be fixed, then the hold stays.
I realise you object that the hold prevents people from increasing knowledge by answering the question... but there is no reason to make that objection. If they have an answer that is good for this question, the same answer is good for your last question. Because your original question is still open, there is nothing stopping people from adding their knowledge on this subject.
It's unclear what your exact problem is. It sounds like you have a good understanding of the death and injury rules (if you didn't, you wouldn't be able to create the flowchart), so when you post a question asking for an explanation of everything about death and injury it's very obvious that the real problem behind posting the question is not being revealed to us.
You are perhaps having trouble with certain corner cases, but you're not asking about those corner cases you're having trouble with. You're perhaps having trouble with when certain rules should be invoked, or in what order of precedence, but you're not asking about the exact things you're unsure of.
This is why some people have said your problem is unclear. Maybe it's borderline, and not actually unclear enough to put it on hold, but enough people think it is.
Any one of these borderline problems with the question would be enough for some people to vote to hold the question. And you're right, if there was only one of these, it might be unreasonable to put it on hold and then keep it on hold. But all of these borderline problems, taken together, add up to needing to put it on hold. The hold period is necessary to figure out what this question is about and whether it really needs to exist, or whether it can exist in another form.
That process of figuring out what to do with a question is required by the community in order to keep our questions and answers to a high quality, and isn't something we compromise on. That may be frustrating. And yes, you're right — it's based on people's opinions. But that's our job: voting up, down, or close based on our subjective judgement. People being of the opinion that the question should be closed is the system working — it would be impossible for a voting system to function without those opinions.
So, unfortunately, it's not our job to reopen questions without having our opinions changed. It's your job to convince the community why the question fits our standards. To do that, you need to accept that our standards are not really negotiable, and then work with us to improve everyone's understanding of the question. Only once the question is cleared up can it be re-judged and it might be reopened. And that process of understanding can't start until you're willing to stop complaining that it was closed, and start helping us understand what value the question has in being a question. To do that, you have to solve at least one of the three problems above (which may incidentally solve one or both of the others):
Tell us why this question isn't too broad. Yes, you've answered it already with a long but not-too-long answer, but that doesn't prove that the best answer is actually short enough to fit on our site. Since we care about getting the best answer, the question must be not-broad enough so that the best answer is not a book or just repeating a reorganised version of the SRD.
Tell us why this question is useful, when the other question seems to do the job already.
Tell us exactly what part you're having trouble with. Our format does much better with questions about very specific problems, and because our format does poorly otherwise, it's become part of our requirements for open questions that they be specific and clear about that specific problem.