If they are "HA", how likely is he to get in on his own? The coaches are in more of a hurry if they need to nail down ED support, less if they don't. The fact that they haven't done pre-reads might mean that it's not so necessary at their school, or that they are waiting on others for ED. How large a roster do they carry? If he would get in on his own anyway, and they have a very large roster, then they may not recruit as intensely as other schools.
Agree that your son has to tell the coaches, "I'm really interested in your school, and would like to visit if you are really interested in me." Since travel is involved, you really have to know where he stands before planning a visit. Hopefully your son is excited about visiting the ones where he has had pre-reads and talked to the coaches, since that's where the love seems to be.
As a note, recruiting at all kinds of D3s continues into the spring; if he's not applying ED, he should be prepared to apply to several schools where he has had this kind of contact with a coach, and keep the dialogue going through the admission cycle.