I think it would be fine to update the charter to include 2D Context as actually within scope if that's what the working group proposes and the Director and AC agree.
I wouldn't object to that. (see http://lists.w3.org/Archives/Public/www-archive/2010Feb/0004...)
Compared to the recent message from TBL: I am asking the domain lead to annotate the charter
Unless there's a massive difference between update and annotate the charter that I'm unaware of those sound like exactly the same things.
I'm not saying that Masinter didn't have any ulterior motives (but I'm also not saying he did). But the facts of what people have said in this debate always seem to get ignored in favor of the evil Adobe storyline.