I agree with rainbow. It is easily possible that Adam is just trying to trick people. I mean they write tricks into the writing, instead of actually building the arcs and the story to a satisfying climax and conclusion. Someone that would be such a bad writer as to write tricks into their writing, is certainly ridiculous enough to lie by omission. The writers are not honest people and, as far as i am concerned, they don’t respect their audience enough to understand that it would be better to not answer the question.
Though i don’t believe anyone is going to die at the mid season mark, i don’t think what Adam twittered proves it either way.