Nice try, but that cannot happen. What would they counter sue for? Inconvenience? If that were the case everyone would be culpable. Come-on! Yes - stupid lawsuits happen but you must take the good w/ bad.
D
Depending on the way the lawsuit against them was worded, they could potential sue for slander (libel too, if the plaintiff made any public statements regarding the same issues). Very damaging, possibly.
jW