Every practicing Catholic recites (prays, if you prefer) the Nicene Creed at least every Sunday.
Therefore every practicing Catholic professes with his lips (at the very least) belief in Jesus Christ as Savior and incarnate God in front of witnesses at least once a week.
And that's the absolute bare minimum. Saying "I'm a practicing Catholic" therefore automatically implies "I believe in the Nicene Creed" which implies "I believe in Jesus Christ as savior and God".
That simply is not the point.
If my appalachian hillybilly relatives ask me if I'll bring some RCs and Moonpies home in a poke, I either know their language or I don't.
This guy had worked there at SA for a while and refused to speak their language. The correct answer was "Yes, I'm a Christian."
"Saying "I'm a practicing Catholic" therefore automatically implies "I believe in the Nicene Creed" which implies "I believe in Jesus Christ as savior and God"."
Maybe you know that but the interviewer might not know that, and being or saying you are "Catholic" does not automatically make you a christian to someone who has no knowledge of Roman Catholic doctrine. Are you a christian is just a simple way of asking are you trusting Christ for your salvation? The interviewer does not want to ask nor need to ask to be instructed in all the nuances of other denominations or faith systems. The candidate may not have gone to confession in over a year and not know whether he is still saved but has gone to mass a couple of times in the year so considers himself a Catholic.