Saying no in a consensus-based organization

Excessive politeness is not something I'm used to being guilty of. The IESG responded to a proposal recently. As I read this response the IESG is saying that it has significant problems with the proposal and wonders whether it is worth spending the time to fix these problems. The IESG is also saying that it will work with the working group if the working group does in fact decide it thinks the proposal is important. We spent a lot of time trying to minimize the feeling that we were not being constructive and to soften our message while still saying what we wanted to say. At least my experience has been that as an AD, your words always have more impact than you intend even when you take this into account. Apparently we over did it this time. The message that got across seems to be something much more muddled and along the lines of "The IESG is going to try and kill this proposal with a series of poorly formed objections that they will not articulate." Communication is hard. Saying no constructively is apparently even harder.