I don't believe her position is the majority either, but you can't just assume it is in a news article.
This article uses BOTH some and many to describe the number who oppose Sheehan.
That is good enough for me, and it is exactly what I would have done. I would never write "most" unless I have some statistics and polls of military families to back me up.
But that's just my opinion...you are certainly entitled to your own in such a matter without any rancor from me over it.