I wouldn't (and didn't) vote to close your question, but I can see why others might have.
The homework and exercises policy is intended to discourage questions that won't enhance your knowledge of physics. The real target is questions where the principles involved are clear but the answer requires a long and tedious calculation. Since no new principles are involved no-one is going to learn anything, and only the person asking the question is likely to be interested enough to read through the calculation. Questions don't actually have to be homework to fall into this category, hence the description "homework and exercises".
At a superficial glance it looks as if your question is about what acceleration is required to stop an object moving with velocity v in a distance s, and this is the sort of thing we'd close. A more careful reading reveals that your question is deeper than this, and it seems to me a perfectly good question that shouldn't have been closed.
So my guess is that your question was closed because the people who voted to close it didn't read the question properly.
Obviously this is bad, but I'm reluctant to criticise the people involved. We get lots and lots of homework questions and trying to keep up with the flood requires a lot of effort from site members who do it on their own time and for no personal reward. Your post is a bit long and rambling, and I can see why the reviewers may have just skimmed it rather than reading it thoroughly.
The way to deal with such miscarriages of justice is to mention them here, as you have done. I have voted to reopen your question, though it will take four more votes before the question is reopened and I note that in any case you do have an answer that you liked enough to accept it.