Why does everything have to be done on explicit contract basis? How can an altruistic act of one party (helping out after leaving the company for free) be turned against them!? Where will this end!? Will I have to get in writing that this was in no way meant as a bribe every if I ever pay a round of beer for a couple coworkers?
There should be protection in place that if people act in good faith they cannot easily be sued like this. And definitely this kind of victim blaming is not helping going in such direction.