This behavior is fairly common for coaches who are interested in a player but are still looking to see what is out there. One email thru the cracks can happen, two is on purpose. I think if they were that interested they would probably be saying hey what time are we meeting that Jimmy kid?
Saw this from schools that liked what they saw from 2019, but were looking for taller guys that threw a little bit harder. Sent one last courtesy email saying that he took a visit to another school and was considering committing. That woke them up and schools that seemed to be getting cooler on him had him on campus within a week.
I would send a final email saying - Coach, I received a camp invite to another school that I've been in contact with on the same weekend as our scheduled visit. Would love to see the __________ University campus and meet the staff but need to finalize travel arrangements. If you could confirm a time so my family can get everything sorted out on our end it would be highly appreciated.
I don't know if you booked a flight or if you can get a refund/credit but I would hold off on making any other travel arrangements for now. The coach knows where your son lives, he knows how much of a haul it is to get there. No response, just don't show for the visit. If they get mad you have the excuse of I sent three emails. And if you never hear from them again well then you have your answer.