Your chart is really quite identical to "chart 2" lower down on his page (if anything his chart looks "more optimistic" and it covers a longer timeframe).
Sure, bitcoin transactions are growing, maybe exponentially if you squint (and maybe not). Just at a rather lower rate than the virtual currency he spotlights and that's most of his argument.
Basically, he is looking at a payment system that is used primarily for, like, payments and showing it's contrasts to bitcoin.
I mean, does anyone really see bitcoin as primarily for payment in today's world?
In fact, my thesis is that increased use of Bitcoin as a currency is partly what is driving down the price. Most of the highest-volume Bitcoin-accepting vendors (Overstock, Gyft, Tiger Direct, etc.) change their Bitcoins immediately to USD, which creates significant selling pressure.
1. If anyone is wondering why the most popular addresses are excluded, it's because those addresses are almost invariably the exchanges, and so they skew the data upward.
(volume being critical to deciding whether the trades are interesting)