Ha, someone else with the same issue! I, too, broke that post (what you guys are calling a screw).
In my case, I wound up cold-welding (ie. epoxy) the nut and half the post to the stub of what was left on the car. It'll be a pain to get off the next time the filter needs to be changed, but that will probably be another 100k miles (someone will probably have to dremel it or drill it or something).
I certainly wouldn't go with only the shield.
My bigger issue is that, since I changed the filter, I've had an issue where in extremely heavy rain, I get a weird engine noise when I step on the throttle. No noise at all when my foot's not on the gas. I'm wondering if I somehow replaced that foam splash shield incorrectly, and if that could be causing it somehow (no idea exactly how... water getting into my gas? Gas not properly getting to the engine?0.