Well I read it, I liked the part where Dr Rieger claimed"...but never straight." Apparently that landed him in a spot of bother because he then clarifies "Never was too strong..the majority of women who claim to be straight are not straight in their sexual arousal." Of those 345 women involved in the study some of them were lesbians already, "whereas lesbians are far more attracted to the female form." So subtract those and you're left with..for the sake of argument 200.
200 women in or around the University of Essex are possibly bisexual.
As you say way too few to qualify as all. Interesting read though, thank you.