If he is going to fly J a lot on CX, perhaps you can consider CX Gold:
* Unless he is doing a annual MR, he may not be able to keep his OW-EM status. If he cannot keep it up, he may lose first class lounge accesses anyway.
* While he cannot have seat guarantee on J, he can have a high waitlist priority on CX. With CX J often full these days, a high priority can be helpful.
* If he flew 30K already on CX/KA last year, you can try to see if CX can comp him Silver from his pre-18 flights. That moves him ahead pretty fast already.
* Lounges in US are not comparable to those in Asia. There are very few first class lounges (e.g. AA's Flagship lounges) in the US. And these lounges are not really good anyway. So having access to business lounges, such as the Admirals Club, should be good enough.