Kissing 'straight' men. Is it a big deal?

Is there anything wrong with two seemingly straight men kissing on the lips? Photo on the left shows Diddy and Rick Ross in an embrace, like they were getting ready to kiss each other. Rapper 50 cent posted the pic on his instagram page suggesting the rap heavyweights are gay. When fans blasted him for posting it and suggesting something like that, he quickly deleted the pic.

Photo on the right shows '12 Years a Slave' director Steve McQueen and star of the movie Michael Fassbender kissing on the lips after winning Best Film at Sunday's Oscars award. The men are known to be straight men with women in their lives (Steve has two kids with long-time girlfriend, Bianca Stigter. Michael has a girlfriend) but it didn't stop people from insinuating they are gay because 'no straight man kisses another man on the lips'.

I personally would not be comfortable with some girl kissing me on the lips, but for someone who is comfortable with it, is it a big deal? Can't two straight men kiss each other? Pls share your thoughts..