I have, all my life, been raised to call the coming Friday (or whatever) "this" as in "this coming", and the one to follow "next" as in the one after this is the next in line. So, to insist that Mark's terminology is not proper communication would be incorrect, just because it doesn't follow your rules, which I (and from the replies to Mark's post, over half the people who read the board) do not ascribe to.
That said, because everyone wanted to make sure that the timing was communicated properly, it was questioned and answered with a specific date, which should have taken care of your misunderstanding. But, since it didn't, I don't think it is Mark's communication skills that you should be worrying about.