For the record, I didn't downvote the question. I definitely think it was ill-posed.
We can't know why people downvote if they don't say, so the following is just a guess at a possible motive for some of them:
Since 4 of the close votes treated it as a self-study question (not mine, I voted 'unclear what you're asking'), I expect several of the downvotes were for not following the self-study guidelines: there seems to be a tendency to downvote those recently (not necessarily the same people that vote to close), even when from brand new posters. This is a tendency I generally disagree with, since the people that ask but don't follow the guidelines tend simply not to know what's expected (people who continue to try it on after having it explained, on the other hand, no longer get that benefit of the doubt -- if they keep failing to follow community expectations after a couple of pointers, I vote-to-close and downvote without compunction).
What I'd like to see happen with a question like that is that it gets an answer that shows how the question is compatible with different interpretations that lead to entirely different answers (since telling people the question is unanswerable rarely seems to deter them). As is often the case, such an answer takes some work to compile. I started one but was unlikely to finish it for a few days (if at all)... and meanwhile the question unsurprisingly closed (making it impossible to post any answer unless the question changes and it gets reopened).
I don't know of a good way within the present format for SE to deal with the situation of trying to show-by-example why an ill posed question of that sort doesn't have one answer, since the site is designed to close them. Perhaps (i) a blog post would be a way of dealing with an example or two of that type, illustrating the problem by given several takes on the question (including takes on what any missing information might be) and showing how much the answers differ, or (ii) to post a reworded/similar question as community wiki, and invite different interpretations as different answers by way of illustrating the problem with such ill posed questions. In either case, later questions could then be linked to it as an explanation of why such questions don't work.
As for why it was protected, chl is likely correct. But protection in any case can be used whenever a lot of low quality answers are being posted from accounts with low reputation; I actually debated protecting it myself (a fair number of users here have that privilege though it's rarely used).