Within the past few years, one respected source that ranks undergraduate business schools placed WUSTL’s undergrad business program at #1. Therefore, if your son is flexible regarding geographic location, he should do well. If targeting the NE US, then be prepared to work hard to get an internship in that region.
I have no specific knowledge regarding WUSTL’s alumni connections, but unlikely that it has a strong presence in the NE US since there are so many excellent business schools in that region whose alumni do have a strong network.
However, your concern is critical if your son is required/requested by the coach to apply ED to WUSTL as it is a binding contractual commitment. Probably not a wise move if one is targeting employment in the NE US.