In general, a positive result from a culture is considered very reliable. I'd be inclined to believe it. As far as the blood test, well, there are different blood tests. If this was an IgG test for both types, then I'm a little surprised at a negative result after 10 months. I'd inquire as to what test was used.
Something you might consider is his getting a Western Blot test for herpes. It looks for enzymes relevant to more antibodies than the ELISA type tests that are commonly used. The WB is available through any doctor or clinic and is done at the University of Washington. To do this, have your health care provider call #206-598-6066 to request the HSV Type-Specific Serology information packet. http://depts.washington.edu/herpes/