I see. Well yes, you have a point.
We are atheists, and my boys non-denominational school did an Easter service this year for the first time in a long time (so I'm told), probably down to new deputy head (whole other story).
I let them go, I even went and watched them (although I was a bit
) about it.
The kids sang beautifully, it was a nice enough 'show' and that was it, no more said about jesus dying on the cross.
They have no exposure to religion at all, not outside school and barely inside school and so I suppose, in the context of making sure they aren't unduly indoctrinated with these ideas, I can live with it. They ask me if I believe, I say no, but many others do and the conversation usually stops there (once I've explained my ratinonale for not believing).
I do see your point, but you are a much bigger influence over your DC so even if they do occasionally participate in worship, does it really matter?