Fake: Super straights (as originally conceived by transphobes) aren't attracted to trans people like they're not attracted to the same gender. It'd be nearly impossible to find a dick that isn't connected to a trans person or a man, meaning he somehow avoided thinking about it until the guy moaned. The sheer stupidity is unlikely, so it's probably satire.
Gay: Not necessarily, as enbies and transfems can have dicks and still use a masculine voice, so sucking that dick could be heterosexual. However, it's more likely to be gay than not gay, as most people with penises and masculine voices identify as men.