These Are X/Y Questions
These sorts of X/Y questions typically confuse "normal" with "safe" or "healthy." These aren't always the same things.
As one example, where I live it's quite normal for deer to jump out in front of fast-moving cars. It is not healthy for the deer, nor safe for the drivers, but it is statistically common enough to be considered normal.
Ways to Deal with X/Y Questions
You could answer the question at face value and cite statistics, or you could address the real underlying question as best as you can understand it. In this case, the underlying question is probably something like "Is ingesting moths harmful or toxic to cats?" Both approaches are valid, and a lot depends on the culture of the specific site.
Whether or not the question needs to be edited for quality or clarity is similarly a site-culture issue. Most sites on SE promote community improvements to low-quality posts, provided the edits don't dramatically change the author's original intent. If a change is needed but would be too drastic, close the question; otherwise, try to improve it to make it on-topic and useful to future visitors.