Camps are predominetly in place to make money and provide much needed funds for their baseball programs. Some programs actually use camps as a recruitment tool, espcially when a HC doesn't leave campus. FSU a great example, they want their potential recruits to come to camp to meet Coach Martin.
However, in most cases it isn't going to make or break your chances if you don't attend a camp. What I am saying, my pitcher was invited several times to camp where he attended, he never went because he was seen at other events. But if this was the only way the coach could see him most likely he would have gone.
However, if this is a situation where the coach and player have both had interest in one another (especially the coach) and not a major expense, why not?
If your son attended the tournament and there were coaches there and gained interest, then that was a good thing, if not, then perhap you need to reevaluate the situation to determine if the invite is really for interest or for the fee. Personally, the whole process works in a way that you really know when someone is interested and someone isn't.
Either way, keep working at it.