"There is no titanium this year, because Apple discovered that it wasn't great for dissipating heat." - This made me chuckle. They didn't discover this, it's been known for a very long time (e.g. Ti thermals). I find it hard to believe Apple didn't know this. Titanium's thermal properties have been very well understood for a very long time. A high school textbook would tell you it is one of the more inferior metals (in any of its alloys) for this purpose.
Apple employs some of the world's most talented people, there's no way they didn't know. They chose it knowing this (for what reasons, likely only they can say).