As background, I am a new contributor to this beta site (found it via HNQ one day), but I have extensive experience on StackOverflow both answering and moderating user content.
I previously became aware of your community's strong suggestion (requirement?) to demonstrate research. The research requirement problem is a struggle across the network. As an aside, I am not sure how someone without medical training could really research the question.
Your site has clear guidelines recommending against answering off topic questions. The meta question linked focuses mostly on medical advice, which you certainly don't need to convince any healthcare professional about.
However, I answered the question because it is:
- Relatively clear
- Not specific to an individual's health factors (although I admit there are some some strangley specific time frames)
- Potentially useful to future visitors
In my opinion, questions that are clear, are answerable with facts and have lasting value should be on topic. Obviously it is not my place to change your community.
I assume the historical lock was applied due to previously decided consensus. The historical lock is an extremely blunt instrument of moderation. It prevents votes and comments on the entire Q&A. In my experience, this is best applied to questions of historical value that are at risk of being deleted.
I ask this because, what if my interpretation of the research is incorrect? Perhaps one day a true expert in radiocontrast might stumble across my post, or perhaps new research refuting it will become available. The historical lock would prevent them from downvoting or commenting.
Thus, in this case, I believe closing the question (or editing it in some way to make it on topic) is the better choice. The Q&A is not at risk for automated deletion because it has an upvoted answer.
I believe questions that are off-topic due to lack of demonstrated research with answers of potential lasting value should be historically locked only if they are at clear risk of deletion to preserve the ability for other users to vote and comment.