Cabbage Dad just my 2cents but here goes just 1 reason to "commit" -- if a player has multiple offers of admission support for a D3 (even those very few elite hA without slots), they can only ED to one school (true for any ED school whether D1 or D3). You can apply internationally, to military academies I believe and also to state universities. So once the player opts to apply ED to their top choice, they let the other schools know they have made a choice and those other offers tend to go away given most coaches have slots and just move down their list. By default, the player has committed.
Now, the player can hope the other coaches take the news in stride and some may offer to stay in touch in case it does not work out. But the player has been through a pre read, and while nothing is guaranteed, it does usually work out. It is up to the player to understand what the chances are that it will not work out.
Now back to the OP -- 2020Prospect -- if it were my son, we would likely not go. The cost of the event is much less than the travel for us, but for you this may not be an issue. What is the purpose of going if your son is already intent on applying ED to his first choice school? If there are schools going that have not seen him that are ahead of his currently committed school, then that would be a factor. If he has suddenly improved in some way, then that would be a factor. But you are nearing the end of your recruiting journey and I am not sure why you would go to an event that is for uncommitted players. If you do choose to go, it might be wise to alert the coaches of his ED school that you already paid for the event, travel etc and plan to go, as they may be there! Or they may find out you did go, given the small baseball world and the fact they are highly selective and HA like many school there,
Meanwhile it is not really necessary to keep the recruiting ball going unless there is a school your son would rather go to (that has not told him no) instead of where he is applying ED. If for some reason it does not work out ED, you have time before ED2 and before regular applications are due to then reach out, perhaps with the help of your travel or HS coach or both -- to other schools then.
Again, just my opinion.