Alright, my two cents:
Mendelsohn's answer to both Greg's gun and his book are fine by me. I would have been far more surprised if Greg
wasn't carrying at this point given all the shit that has happened to the team. And while he may not like guns, as a smart man he knows carrying one might save his life or the life of his teammates. For me, that's explanation enough.
As for the book, his not finding a publisher is actually fairly accurate. From what I gather from what has been shown, he's an amateur author who wrote a history book. I don't know the style that he wrote in, but a publisher might be unwilling to take a risk on something like that. In contrast, Langston wrote a book that looked like a crime/medical drama. That's an easy sell as an airport novel. A publisher probably felt that Greg's book would have a harder time reaching an audience.
Finally, about Greg's family. I find the idea that there has been no family visits from him or relatives to be hard to swallow. These characters probably do a lot more in the days, weeks, and months when we don't see them in episodes. They get days off, sick leave, vacation time, etc. I'm positive family visits have occurred at some point throughout the seasons. Just because they haven't happened for us to see doesn't mean they don't exist.
And that's all I have to say about that.
