The thing is,s I'm not sure you can expect one. After all, I know if I were a showrunner for DD I sure wouldn't feel the need to explain in detail why DD wasn't around for JJ, or why he didn't help out in Age Of Ultron, or even why he seems entirely unaware of inhumans popping up around the globe. Because those are all plots of other properties that DD doesn't nessisarily belong in and I sure as hell wouldn't want to have other showrunners/writers/directors forced to shove my character in just because it happens to occur after my TV debuted. Just as I (as a showrunner) would be upset if hey were like, "hey we've decided to do this Hawkeye special so we need you to use Barton and part of his plot in one episode." Now if it were optional and I had a place for him, no problem. If they came to me before the project started and Hawkeye was always part of the pitch well, that's fair. But if I had, say, a very personal story entirely set around the idea of my main character needing to deal with this trauma on his own terms and suddenly I absolutely had to insert another hero we're going to have trouble.
Now asking for an explanation as to why DD had no idea about Killgrave is not as big as having a mandatory cameo, but at the same time I could do without the forced clunky exposition. Just like I don't think the movies nessisarily owe us any explanation on where other heroes are, especially when a reason is easily assumed from the plot (ie: IM3 - Tony was believed dead and wanted to get revenge against The Mandarin on his own. CA2: Steve has been labeled a traitor and isn't sure who he can trust) and in those cases the heroes actually know one another. DD doesn't know JJ, he doesn't have any sort of Big Brother set up that monitors the whole city and even if he did he couldn't be everywhere stopping all crime at once.
So, personally, I can pretty safely reason that DD was not around to deal with Killgrave because he's just one guy in a suit and not even a multimillionaire with tons of free time and contacts and access to police records and street cameras or anything like that. It's totally believable to me that DD could somehow manage not to know every single thing going down in the city. I mean, honestly, it's almost better if they don't address it since if you think about it...Sure, he likely would have been aware of Hope's case, but still it would require him to believe Hope's story (and remember that Luke Cage - a man with actual unbreakable skin - found the idea of mind control ludicrous) and then actively pursue an investigation. For the record, JJ had personally dealt with Killgrave before and he was stalking her at the time and yet he was still a difficult man for Jessica to track down. The first like 5 episodes of JJ were all about finding someone not crazy or high who would admit that Killgrave existed using a girl he was obsessed with, a lawyer working for a powerful law firm, and a highly public homicide case. Oh, and tracking him down wasn't just something Jessica was doing after work, it was her full time job. Matt has absolutely NONE of that. He does have a day job and while he's a lawyer himself he doesn't have nearly as many resources at his dispose as Jerry. He has no personal connection to Killgrave and none of the knowledge Jessica had going into the case. He could walk by Killgrave on a daily bases and wouldn't be able to recognize him, not unless his senses are now so super that he can tell the slight rhythmic difference between a psychopathic mind controller's heartbeat and every other New Yorkers. Basically by asking that Matt was aware of the Killgrave case you're also forcing the writers to admit that, actually, he totally failed at that investigation since we've seen the end of JJ and, spoiler warning: Matt does not show up at the end to save everyone. So, yeah, as a showrunner I would probably avoid adding unnecessary exposition just to explain how my main character totally failed at a mission that the audience will never see him work on at all anyway.
On the other hand, if DD2 and JJ take place at the same time than the series writers might feel boxed in with certain elements like how much trouble they can cause in Hells Kitchen and what they can do with the character of Claire (I mean they wouldn't kill her but death is hardly the only character changing event that one can go through). And even if they are simultaneous, as they totally could be, I doubt it gets referenced for much the same reasons I mentioned above. This is Matt's story. Unless referencing what is happening with Killgrave somehow adds to what is happening to DD it just wouldn't be relevant or necessary. It's just forcing the writer's to add something into the story that doesn't need to be there. Not to say that they couldn't do it and it couldn't come into play organically, but just don't expect it to be a detail they even care to deal with.
