True, but I doubt the meaning behind placing to cross there was anything less then a stab at the pagans/wiccans and had some thing similar been done to a mosque or a church that there would have been a greater out cry over it.
I don't think it's possible to say what the motive was for leaving the cross behind; it'd be kind of a pointless debate. It could be an attempt at proselytizing or a reminder of what the Christian who left it there believes is the only true religion, but to view it as something malicious I think takes a distortion of the truth considering it wasn't vandalism or hate speech; just the planting of a common religious symbol unobtrusively. Thus I'd say the phrase "stab" is entirely inappropriate.
In fact, if someone left a pagan symbol in the pews of the local church (which I would say is an equivalent action) do you really think we'd hear about it at all?
That doesn't mean I don't disagree with your point. If something happens against Christianity it's going to be wider reported than if something happens to another religion. There are simply more Christians so their interests are more pervasive. This is still a step in the right direction, and I'd rather save my offense for when/if something worth my outrage actually does happen.