Actually the story sounds more like she was fired for eating pork on company premises - not for being Catholic rather than Muslim. A company can pretty much dictate what you do on company premises (assuming that they aren't asking anyone to do anything illegal). What will get a company in trouble would be terminating an employee merely for belonging to the wrong religion, at least as long as the employee wasn't using that to avoid doing their job (eg, refusing to do their work at a defense contractor because they've decided their religion requires them to be a conscientious objector) or bringing their religion into the workplace in a confrontational way, or something else like that where their religion was preventing them from performing their job function.
Consider this for example: If you're the proprietor of a kosher Jewish deli, you probably don't want your employees bringing pork into the establishment since it would make it difficult or impossible to maintain a kosher restaurant.
Having said all that it does sound like rather much of an overreaction for an electronics company to have that kind of policy and that kind of reaction to that situation ... however it would be perfectly within their rights as long as the incidents in question happened on company premises.
Any 2-bit attorney could blow this false premise out of the water in court and prove with a preponderance of the evidence that the real reason was her religion.