This research was deemed necessary as the official line for the past few years has been that research proves that bisexual men are 'really' exclusively gay, and just pretending to like women for social reasons - see this 2005 article in the NY Times. I think enthusiasm for this point of view was fueled by misogyny (of course men are just pretending to like women) and/or homophobia (one step out of line and that's it). I think it's disrespectful to people who self-identify as bisexual to deny they are telling the truth.
This is my big problem with the saying 'an anecdote is not data'. If an individual experience is not replicable in the lab, nevertheless it may well exist. The experiences of people who are seen as 'other' are not considered real (they are anecdotes) until they are observed by official means (they become data). In this case the 'official means' of verifying sexuality is measured tumescence on viewing porn. But porn is not politically or socially neutral. It reflects many issues as well as sexual arousal - such as anxiety and projection by objectification. I personally dislike most heterosexual porn, although I am heterosexual. Does that mean my identification as a straight woman is a mere anecdote?
Anyway. Bisexual guys - you exist again. Carry on.