To be honest that doesn't sound like something anyone would ever say. I came up with a similar answer as you because I didn't know the idiom, but the idiom sounds 100x more common.
In the example Honemens gave, the presenter would say something like "I will answer your questions later" or "Hold on to your questions until I'm done" or "There will be a Q&A session at the end".
Another way to read the sentence is to read "danach" as "da + nach". The structure "nach etwas fragen" is like the English "to ask for something". In this case, since "something" is "it", rather than saying, "Du musst nur nach ihm fragen", you can instead change "ihm" to "da" and combine "nach ihm" as "danach". If this is confusing, a quick internet search for "da compounds" should help to clarify the issue.