[gruseom]

I'd give him the benefit of the doubt. Sometimes people quote things in that way because they're huge fans and the source is taken for granted in their world. They think everyone knows it and those who don't, should. (I've done this myself and realized later that it looked like plagiarism, which dismayed me because my intention was exactly the opposite, to honor the source by acting like it didn't need to be mentioned.)

Blog titles are also a common place for people to adopt cool quotes that are particularly meaningful to them - it has almost become a little genre - and it would spoil the fun to footnote them. This guy actually has quotation marks around his, so he's more punctilious than most.