Can information theory be applied to human interactions and communication?
Information and signal detection theory are commonly applied to cognitive situations. Examples include TSA agents searching for weapons among carry-on bags and sonar operators attempting to discern ships from fish. In addition, information theory itself is highly general, and has been proven to apply across disciplines. So I do think the premise is valid. 

However, the example does not list an application, per se- it simply describes a situation where one might think about coming up with an information-theoric approach. Such an approach would certainly involve a lot of research because there are many confounding factors in communication between humans (not the least of which is the cognitive framework of the receiving individual). You would need to carefully define what is signal, what is noise, and where the boundaries lie. I contend that this would be particularly difficult in the general case.