The note was posted on his (Bad Robot's) Twitter page, so in a way it's like double the effort or double the self-branding, depending on your perspective. It's a weird thing, paying respects in the social media age, especially if you or the one you're paying respects to are people of note.
I mean, what would you people criticizing Abrams have wanted him to do?
140 characters or less in twitter form. It means way more than hand writing a note.
Would people be less offended if he had written it on a piece of printer paper? He obviously cared for Anton a lot. Probably wrote it on the first thing he had sitting around. Outrage over nothing to me.