Yes, this is another wonderful trick question that we'll have to deal with in everyday life as a DBA.
Perhaps, in some countries, where there are 100 million Oracle DBAs and 120 million SQL DBAs, then people have to trick each other to see who really knows his/her stuff, as everyone is a DBA looking for a job and employers have to ask really tough questions.
How many more questions are we going to see like this? It helps no one.
It helped me, in the sense that I was reminded that you can't take a backup of a snapshot. But I agree that the benefit was incidental given the trick nature of the question. In other words, the question was helpful in spite of, not because of, its tricky nature.
Maybe there is a way to balance trickiness and pragmatism in the questions. I've never tried my hand at a question, so I'm limited in the criticism I think I am entitled to give.
A SQL query walks into a bar and sees two tables. He walks up to them and says Can I join you?