Stalker TV show and Social Media????

From my understanding companies with products have to pay to be featured in a tv series or movie, so when they don't want to pay to be in the show, the show creators end up making up a similar product and name it something else. But what I dont understand is how Stalker got away with making a fake FB layout while calling it FB they even did the same to Tumblr. It seems like the lawyers from both FB and Yahoo(owner of Tumblr) would be pissed off about it.

Hard to be too pissed about free advertising

Parody law............