Yeah, that narmed me, too. Like some overzealous editor got halfway through changing it from one to the other and then got distracted.
I also find it a little wonky that a PC is expected to sink so much GP into construction when GP is such a closely moderated resource. I mean +3 armor, or a castle that gives me a non-staking +1 to some CHA checks on the off chance the DM happens to let me make some CHA checks in my castle?
That's kind of a problem with GP in 3e and 4e in general, though.
I do like the article, all told, and it gets me thinking about giving out strongholds "for free" to characters just as a lark. Not sure I would use the rules therein, but it's a useful story item to consider, and I like that there's an article for considering it.