Race day logistical question for spectators

I am doing the Buckner Mission Man Sprint tri tomorrow. It starts at 8am and I'll leave home at 5:30 to get there early enough to set up, etc. My wife wants to come watch with the kids (2 and 4) but only wants to leave to get there probably right around or soon after start time. In my info packet it says "we will reopen the park at 9:30 to allow people to leave"- does that mean that the park will be closed to spectators who arrive after the race starts? That is, if my wife gets there after the race starts, will she be locked out? I have never done a tri before so don't know what the general situation is. Since it is a public location I had assumed my wife can arrive whenever she wants (getting 2 little kids out of bed and loaded into a car early in the morning does not always go as smoothly as you would think! haha). Do they usually cordon off the area? I have looked for an event organizer phone number but can't find one. Any thoughts?