As a designer I really do feel there's still a chance that it's an honest mistake, because I could see myself accidentally creating it and I've never heard of Kekistan until this thread. The K letter's form lends itself to being flipped; look up "KK monogram" and you will see it's a common design pattern. The typography of this logo in Destiny is futuristic, and in futuristic type you often have the letter E split into triple bars or otherwise having a piece of that letter floating/broken off. Look up "futuristic typeface". As a designer, I would probably go with the triple bars between the two letters because it lends itself to being ambigramic and ambigrams look cool. With that said, if it was coincidence then they failed terribly in doing the ol' designer Google look up to (a) Know that your work is original and (b) That it doesn't stand for anything terrible.
Again, I've never heard of Kekistan until now - they can go fuck themselves. I'm just trying to give a designer's perspective on how it could have arrived to this design without any sinister intention. I am not an apologist. I can imagine that if I were not a creative then this would 100% without a doubt be a blatant homage to the racist group, but as a designer having had to work within certain constraints (ie futuristic) I can imagine myself accidentally creating this were I dumb enough to not research the letter combination ahead of time. So yes, they should take the blame for not doing the research, but firing the guy? Only if they can prove that it was intentionally done. For all we know the designer didn't intend on the four bars between the two K's to represent an E. Is it literally spelled out as KEK in the descriptions anywhere?