I doubt any of the rulers at the Field of Merrilor on the eve of Tarmon Gaidon will care all that much about the fact that the Oath Rod cuts down a channelers' life span (some might even think that's a good thing).

I'm of the opinion that Cadsuane is among the Sisters who would think the Oath Rod is still important, even if it negatively affected her lifespan - she doesn't seem like the type of woman to be horrified at the thought that she might die after having lived a long and very successful life.

I just don't see him really having a reason to bother to address this in front of everyone else. It only effects the Aes Sedai and while it would be nice to make the Oath Rod unnecessary & revise the Oaths, I'm not really sure that this would be something for Rand to take up with them at this point in time.