Though actually I didn't see the reference to that in the OP before you mentionned it.

It sounds likely they're in the correct order, though. I could see the motive for an out of order list, but it doesn't sound much like Harriet nor Brandon to give us the chapter titles out of order, when they know how we love to speculate on anything and how we hate to speculate on what we think are facts when they're not

So I would assume they saw right away we'd take this list as "major" hints to speculate about the book, and would have told us from scratch if they're not in the right order. It's especially not like Brandon to let us speculate for a month and more only to come and tell him : "Btw guys, you did this for nothing because the titles aren't in order". As Brandon said a few times, he loves speculation but he doesn't enjoy misleading people's speculation (to the point he has to fight urges not to redirect people who are too far off, he said at a signing).

Also, there's the fact that previously they've always given us that list in order, and Harriet puts it at the books' opening, so obviously to her the spoiler value of the chapter titles is quite low.