It was a homophobic comment. The whole premise of the "joke" was that a gay relationship is worthy of mockery and that Trump and Putin are gay, and as a result, are less credible as men and leaders.  What makes it even worse is it was scripted and rehearsed, not an adlib tossed in without thinking.

And there's nothing wrong with the FCC investigation. The FCC has to investigate all complaints, that's their job.

Colbert's behaviour is typical of many Liberals. Liberals love to quote Michelle Obama with her "when they go low, we go high".  But many Liberals always resort to sexism, racism, homophobia and the worst kind of identity politics in their attacks on people they disagree with.  It's ugly and unnecessary.