what does DOJ policy say about the Presidents son asswipe?
Uday was ordered by Trump to lie about the June 2016 Trump Tower meeting...so it was Trump who committed the criminal act, and according to the rules under which Mueller was operating, couldn't be charged.
There are however 13 other investigations that you don't even know about, spun off of Mueller's.
One of those could very well be an investigation into Uday's actions.