Fundamentally, for a service to not be discriminatory, it must be regulated like a utility (e.g. telephone, electric, etc).

Using something that has the same functionality as a utility but is not regulated as such raises some questions.

Also, profiling social media is nothing new. It's not uncommon for insurance companies to hire private investigators to look into suspicious cases. One case I heard was a man going on disability citing being homebound but the private investigator found evidence completely to the contrary. I fail to see how this is any different.