First, not obvious but when you turn a bike upside down , the highest point is the top of the tyre, then the pedal, neither exactly suitable for the job. Even the bottom of the pedal is still 5-7" lower than the top of the saddle, besides you would need to secure the pedal, doable but a bit more complex.
Next, the reason the bike stands very firm (if guyed down correctly) is the same why a single pole pyramid tent stands up, vertical pressure. Again try it...(helps if you secure the brakes)
I came up with something like this last year when a mate that happens to design tents for a living (not HS) wanted to make a cycling friendly tent for himself. (security was important for him)