To a large extent you are how you define yourself. If Craig thinks himself to be straight, even though he has gay sex in addition to straight sex (and he has children), he might be confused, he might be in denial, but in his own mind he's not gay.

In wartime, soldiers have been known to have homosexual encounters, and yet when the war is over they return to strict heterosexuality (see the aforementioned Kinsey report). Are they gay or straight?

(A similar example is someone "born into the wrong body." Chromosonally they might be female, but mentally they define themself as male and consider themself such. Even after surgery and hormonal therapy they would still, chromosonally, be female. But this is an area the courts will have to someday decide, and I'm glad it will be up to someone else.)

Craig is, I'm certain, straight in his own mind. Others, however, view him as a liability.