It seems to me you have a lot of info on this group and it's all negative, this type of program is happening in many schools across the country and there is nothing illegal about it. Have you attended enough of these meetings to discover what you're tell, or is it just things you're being told, second hand biased opinions. I would think that this group of people (who I commend for their efforts) would not over react to any other groups coming into the school and doing their thing. I know teens can get over zealous about what's going on in their lives, and I'm talking about on both sides of this issue, but I bet there are teachers there keeping an eye on this group so they can't over step their bounds. Besides what's the big deal, they are doing what they believe in and what they believe will be good for others. No different than you wanting to teach others they are wrong, equal ground for differing views.
God loves those who believe and those who do not and the same goes for me, you have no choice in this matter. That puts the matter of total free will to rest.