That is interesting... and rare, I think. I mean, tbh... I can only assume that they don't genuinely believe, regardless of how 'strict' they are, that the Catholic way is the right way... or they wouldn't be raising their kids in a different religion. Though, how they intend to remain 'strict Catholic' but raise their kids mainstream or non-denominational Christian is beyond me... I don't see how kids would really become invested in it if their parents aren't, aside from when they explore and study on their own as they get into teens and young adulthood.
I still think for the most part, if you truly are devoted to and passionate about a specific religion or belief system, you will raise your kids the same way, as how could you not when you truly believe it is right? Religion is so different than, say, political beliefs or general morals... with religion, when you truly believe in it with all your heart... you believe you are dealing with someone's eternal life after death, as well as their well-being and blessings on earth. I can't really see a parent fully believing and not passing it on to their kids in every way possible... it's like saying, "I want my kids to be healthy, but I won't step in if they want to drink poison... they have free will..."
Of course you wouldn't. Since you KNOW with every fiber in your being that poison will kill a child or make them sick, you will certainly do all in your power to ensure they don't ingest it.
However... let's say you don't really buy into the whole organic-foods thing... well, you'll be sort of ho-hum. If they get some, great. But you're not going to be adament that they eat it. That's sort of like those who aren't decided on a religion, or aren't very invested in a religion. If their kids discover a religion that works for them, great...but they aren't going to insist on it, because they aren't convinced it's vital or even necessarily true.
(No... I am not comparing those who don't raise their kids in religion to those who would feed their kids poison.... I was trying to draw a comparison with something that all of us can relate to as something we would, without question, be vigilant about because we KNOW the effects it would have on the child. Many people who believe strongly in a religion would be vigilant and passionate about teaching/raising their kids in it because they TRULY believe it to be 100% true.)