Disclaimer: I am not a lawyer. Not even once.

If I remember correctly (from reading about this, not experiencing it!), if you counter-claim they will either

> drop it

> sue you (must occur within 2 weeks of the counter claim)

I have no idea about how this would proceed, but if they do sue you you'll need all the fun that entails, which may be a whole load of work.

Frankly it does sound like complete BS, but the question is do you want to be the one to fight it, and could a good lawyer on their side make it stick? I feel like the law is still very much struggling with this whole internet thing, so if I were you I'd be apprehensive about assuming rational through would prevail.