I can understand your pain in receiving such issues. However, I am not completely sure there is much we can do about it. Here is why:
The recognition if something is code or not is not a trivial task and despite our try to improve the algorithm it can still sometimes fail.
You consider JSON is not a code, while this is also a questionable statement. For example, in some languages, it is a valid code. And that’s another big question should we only recognize Java code in Java files
The other point. Why would you need JSON in the comments? Is it to document something? Maybe Javadoc could be a better solution rather than simple comments?
And last but not least it is Ok, to mark issues as False Positive or Won’t Fix. If this rule brings more noise than help, just remove it from your quality profile.
Meanwhile, from our side we’ve noted, that Algorithm is not behaving well with JSON, so we will try to improve it one day.