Why was this closed as off-topic?
Seems to be perfectly on-topic.
I talked with Shog, who deleted the question and he explained that he didn't think this was a very useful test case of the topicality of viruses in ebooks questions. It certainly didn't show much effort. Here is the text of the question for those who are interested:
There are many eBook formats. Are any of them incapable of transmitting a virus?
What problem is the question trying to solve? There were a few answers, but no way to know if any of them provided actionable advice. The question just wasn't concrete enough about criteria to know.
Nor was it a very useful question for figuring out what was on or off topic on the site. It was closed by 5 members of the community. Presumably the reason was as one of the commenters noted:
This question appears to be more fit for Security.SE.
However, as asked, it wouldn't really fly there either since it was rather nonspecific about the nature of the threat. A little-to-no effort question like this would probably be closed anywhere. It's not a good question to determine the scope of this (very new) site.
Perhaps more importantly, especially at this stage, is that the question seemed to be motivated more from idle curiosity rather than an actual need. Nobody (at least not today) is making their decisions about which format to publish or consume based on virus vulnerabilities. Issues like reader support and suitability to the content are vastly more important than the theoretical possibility that a bit of malicious code might be introduced somehow.
Stack Exchange sites work best when questions are surrounding some task that a person is doing. Answers should solve real problems and not hypothetical ones.
Just to be clear, the executive summary of my answer is: the question is on-topic and should be undeleted and (possibly pending edits to tighten it up) reopened.
Three concerns raised by @Jon (who argued in favor of deletion in another answer) were:
[main one] The question was not a "real question", not pertaining to a real problem arising of doing a specific task.
To address this concern: I know several people (myself included) who very explicitly make choices between different formats which they consume based on security risk (Avoid MS Word docs like the plague; prefer to avoid PDFs). So this seems like it falls fully within "real specific task users face".
The real question/task is
"given an ebook in a specific format, how do I assess the security risk of getting a virus from reading that ebook."
"Given an ebook in several formats, how do I choose the least risky one as far as avoiding possible viruses?"
The question is better off being asked in the more specific form of "Can MS Word ebook transmit a virus?" "Can PDF ebook transmit a virus?"
To address this concern: Ordinarily, if these questions had different answers, that would be entirely correct.
But ALL those distinct questions really have the SAME answer ("if the format supports scripting, the risk of a virus is higher. the risk is never zero"). So splitting them up into several questions would merely worsen the information:
At best, we would have essentially duplicate answers. As a matter of fact, I would probably flag the second of those questions as a dupe.
At worst, we would fail to serve the need of some information seeker, who has the same question but about a third, yet-unaddressed-in-specific-question, format.
Admittedly, changing the question to a more practical "given an ebook in a specific format, how do I assess the security risk of getting a virus from reading that ebook" may have been a good edit.
The question fits better on Security.SE than Ebooks.SE
To address this concern: From my experience on other SE sites, the overall rule for migration isn't whether the question fits on the end site, but whether it does NOT fit on the source site. Above, I am trying to argue that this question fully fits on Ebooks.SE
The problem is not that it is not on topic IMO but rather that as phrased it is a "Gorilla vs Shark" Question. While not as obviously contentious, it is still more likely to spawn debate than constructive answers.
I think the question could be asked as "What are the attributes of an EBook format that reduce the risk of virus infection?" But that really is not on topic here. As noted that question is about the nature of the software virus infection and not about EBooks. That question as noted would be better asked on Security SE and I think should be off topic here.
Now if you have a specific example of an EBook that has been contaminated with a virus that has affected E-Readers, and want to ask a specific question about addressing that problem I think it would be on topic here. The reason is because that is an Ebook specific issue that can be addressed actively where the other question is a general threat that is not specific to EBooks other than you arbitrarily decided to limit the scope to Ebooks. But the question and answers do not change when you change the scope to some other arbitrary choice.