I don't know if that seems obvious. They were talking about twitter the social media platform... I can't think of a single thing twitter has got going for it outside of the size of the message, and the size of the message isn't a huge advantage considering often times users use image macros rather than text (which completely destroys the space efficiency) and you could easily just have, say, size limited facebook posts or something similar.

Honestly, I stand by my estimation that interplanetary communication will probably primarily be done over email.