has he been tested yet to know his status? Be sure to ask to see test results since herpes testing is not a part of routine std testing. He might only think he's been tested for it in the past.
Hsv1 genitally typically doesn't reoccur as often as hsv2 does as well as it doesn't shed as often to be transmitted to a partner. The odds of transmitting hsv1 genitally to a partner are rather low though I'm not sure we have actual odds of transmission since it happens so infrequently. Certainly knowing a partners status is important so that you two can make informed decisions about what precautions to take. Also since most adults do not get tested for herpes, making sure you know a partners hsv2 status is also important.
keep asking questions! Also if you haven't already, google the free herpes handbook by Terri Warren and read the genital hsv1 info in there too!
grace
Where do you find the information you give?
It is believed to be less than 2% chance in a year of sex.
He is just as likely to be infected by the 60% of women who have oral HSV1 through oral sex.
Further if he already gets oral cold sores, then his existing HSV1 provides immunity from a genital infection.