So this happened in Glendale but you blame it on "LA?" CA. has a 2-plate law, period. If you have a nice sports car and don't want a front plate, you can keep it in the car and put it on the dashboard when you park. Or use adhesive velcro tape on the front bumper and plate and install it when parked or to get a ticket signed-off. Drilling holes in the bumper of a Porsche would be pretty stupid when there are so many other options, tow hook mount, etc...
I've had plenty of cars out here with no front plate, if it's CA. registered, you risk a ticket. That's the law. It doesn't happen much. It has happened to me in Minnesota, (most states have a 2-plate law), but never in CA. with an out-of-state car no matter what the law is in the registered state. Meter maids only write them for home state violations.
This is such a non-issue in any size scheme of things...just pay the ticket and consider it a "vanity tax."