Recognizing one human among seven billion by their DNA would probably take an unwieldy large amount of recognition sequence. Releasing a weapon with a killing payload and letting it be subject to natural selection risks it evolving to kill more people, or all people. In general, bioweapons are scary because they can't by their nature have reliable off switches.

They are also a heap of excessive effort when a sniper rifle or drone missile works fine.

Actually, genome editing would rather provide a defense against such an attack as you could specifically augment your DNA to look like someone else or be heterogeneous (within limits of autoimmune responses).

I also fail to see how it could help to create something like FOXDIE (I have only read a short wiki article about it)? I mean you can create viruses with a certain sequence already now, so is no clear connection between creating a targeted virus and genome editing? Sure, you can edit the genome but injecting a single malicious gene is much easier (which seems to be the case for the fictional FOXDIE)

Let's hope you don't have a matching DNA sequence.