I suspect that the comments are negative because the word Pivot is being used to generate buzz without substance.
That's the point of the post, and it's an impressive achievement. Read Tony Hsieh's (Zappos) "Delivering Happiness" if you want to appreciate how hard it is to build a business on drop-shipping, and how hard it is to move to full inventory.
I realize this isn't a battle worth fighting, but everyone needs to stop being pedantic over the use of the word "pivot". It had meaning before Eric Ries used it, and it will continue to have intrinsic meaning no matter how narrowly it's defined in the context of the Lean Startup movement. The business changed directions. Let the man call it a pivot.