Yea, I see where you're coming from. This would be pre-recorded content and you are right, idols have gotten flack for having "personal" fan content during enlistment. I personally find the censure attached stupid, but I guess some people see it as selfish and trying to capitalize/make it yourself about then your military enlistment is suppose to be for the nation.
I always thought it was weird too, especially when it comes to videos and music. Like I heard Baekhyun was made to apologize for videos that he made before enlistment that were meant to be a comfort to his fans. People acted like it was some scandal and a cheat of the rules. It wasn't even a release that would bring income and they were prerecorded! If an idol premade things and isn't actively working during enlistment, I don't see what the problem is....