Hi, him giving you oral would not be any risk since he has it genital (genital correct?). You giving him oral, from a one time affair and no breakouts would be considered low risk and not something to be overly worried about. Also depends where his breakout are as even through shedding can occur anywhere in the boxer short area, breakouts tend to be in the same spot, give or take an inch. So if you avoided that area during the oral would also lower your risk.
Bottom line is that hsv2 perfers the genital area and getting hsv2 oral is not common.