That and summer definitely isn’t the time these parks are understaffed. Six flags will be just fine the second school lets out in 9 more days.
Universal also pays better and is way better to work for (not that they’re competing for staff based on how far they are away from one another).
They would also be having massive hiring events like they had several weeks (maybe 2 months now?) ago. Which they aren’t. I do wonder what the in-park staff (ride ops, merch, F&B, etc) who were hired a couple months back is doing just sitting on their hands waiting for a start date. That’s gonna be crazy to plan for their livelihoods.