There are different blood tests available and not all of them are "type-specific" which is what he should get. The most accurate of these (and also the most expensive) is the Western Blot. HerpeSelect can be done to check for either type or both types and is virtually as accurate and less expensive. He should talk to his doc and the lab who will do the test to see what is available to him.
HSV-1 is the most common cause of oral herpes but oral/facial HSV-2 is also possible if he performed oral sex on someone who had genital HSV-2 and was shedding the virus at the time (which may or may not have shown as visible symptoms).
I would recommend he get a swab culture test on one of the sores, preferably within 24-48 hours. Unfortunately the swab cultures are notorious for inaccurate results (could be a false negative, but positive would be accurate), but it still might be worthwhile getting the test done even on an older sore if the doc ordered a PCA DNR swab culture (which I think is probably standard now but it wouldn't hurt for him to check).
If it comes up again he should definitely get in to his doc within 24-48 hours and get a swab test done. This has the chance of getting the most accurate diagnosis on these nose sores but if it is herpes he might have to do this several times before it returns a positive result, and a negative result can't always be trusted to be accurate.
In the meantime, he could get a type-specific blood test done. The advantage of the blood tests is you don't have to be having an outbreak to get the test done. The problem, however, are that it can take up to 12-16 weeks for enough antibodies to accumulate to be detected and return an accurate result. So false negatives are also possible within 12-16 weeks after initial infection. Also, a blood test will tell you IF you have a particular type but it won't tell you where it is (e.g., mouth, nose, genitals, etc.).
It could still be worthwhile to get a blood test now though, because then he'd probably have a "baseline" of knowing if he already has HSV-1 or HSV-2. Then get tested again down the road after 12-16 weeks and see if anything new shows up. However, if he already has HSV-1 and his nose is just a spreading of this, a blood test won't show that. It might still give him some useful information though.
I hope that helps. Keep us posted how he's doing and what he decides to do.