Setting aside the specific case of akulahawk, who I know only though interactions on this site, and who seems to be quite a fine human being, I perceive the term "very straight" to conceal a bias... it's an aggrandizement of certain brands of manliness... the rugged individualist, the macho tough guy, the 'tough-as-nails' Drill Instructor type, the Marlboro man (before he wasted away with lung cancer)... the quintessential alpha male.
The bias is the linkage of those cultural personas with sexual orientation... as though to be badass, Chuck Norris type, means that one is also straight... that gays can't be tough guys, manly men, firefighters, bouncers, etc.
This is the kind of bias that I recognized in myself awhile back.
Gay and straight are binary, mutually exclusive conditions. People who flaunt their sexuality, or who manifest certain traits or characteristics that our culture considers to typify manliness or womanliness, are no more or less gay/straight than those whose orientation is externally ambiguous.