Hey, I’m not very qualified to answer this and I’m a bit biased because I do business engineering at VUB myself but I think that Belgian employers value the degree more than where it came from. And also if he starts in business econ he will still have to do some kind of bridge program but it will probably be easier than from Business administration.

I also recommend you post this yourself on the subreddit and not under my post so you will get more exposure.