Seems like that still screams “gun case” to anyone who cares to notice. I have a short grey case just like it but never felt like an 18” or 16” carbine like that was small enough to fool anybody.
That’s why I have a few different 9”-12” setups with folding stocks to carry in a backpack though.
It's actually worked out really well. It has been on about a dozen business trips. If you walk on the hotel looking dressed business casual rather than a 5.11 catalog, people pay zero attention to the gray case.