What is bhramcharya or 3rd percept?
Abhramcharya means non-celibacy. Avoiding bhramcharya is not the 3rd precept within the Five Prevents. Avoiding abhramcharya is for monks or for strict followers of the Noble Path following Eight or Ten Precepts. 

As for Ud 6.8, it does not appear to be about celibacy but about attachments arising in the mind due to celibacy. In Ud 6.8 (Ganika Sutta), there are lay people involved in immoral sex. Then the monks became morally outraged by this and criticized to the Buddha those lay people involved in immoral sex. Thus the Buddha remarked: both the immoral laypeople and the monks disturbing their minds via aversion to immorality are both on the wrong path.