I never imagined there would be any regulation for cable networks content, but apparently the FCC has come up with a host[1]. The equal opportunities rule [47 CFR 76.205] and what is left of the fairness doctrine seem to would have been violated, were Facebook regulated as cable.

[1] https://www.fcc.gov/media/program-content-regulations [47 CFR 76.205] https://www.law.cornell.edu/cfr/text/47/76.205