IMO, it all depends on what you want to learn and take away from the exercise.
Like what others have mentioned, it can be done with self discipline with any size of memory card.
What is the take away lesson from it?
That the camera has only 30 shots? ...duh... (pointless right?)
Instead, if the exercise is to be more conscious of the basics of photography :
Exposure; WB; aperture and shutter speed; framing and composition; Looking for good light
Then it can be done in a multitude of ways and in fact, reviewing a shot immediately after taking and/or experimenting with various angles/settings can be more beneficial.
At the end of the day, its about being thoughtful of what one is doing/setting.
Emulating the restrictions of film or using a film camera means nothing to improving one's photography.
I can just snap away 30 shots on film as well, or make wrong assumptions on settings and not know.
Did I write all the settings down so that upon review when the negatives are developed in a few days, I'd learn from it?
So in the end, to me, its one's discipline and conscious learning that is important.
Not an emphasis on the gear used (or rather the non-gear in this case) by using a smaller capacity memory card