This logic is always funny. Fun fact: Motorcycles don't have a reverse gear, and lots of motorcycles are extremely heavy. So if you end up facing down hill and something is blocking your way? You're stuffed. You can't even get off and walk away because the bike is liable to roll forward off it's stand.
Do you know how motorcycles solve this problem? Don't do it! Just don't get into that situation. How do you do a hill start? You don't. If you're really forced, you can try, it'll be difficult but often it's just easier to avoid the situation.
- Uphill starts are easy compared to a manual car as you operate the rear brake and accelerator using different parts of the body
- Stopping facing down a slope requires the use of the brakes and a supporting foot, same as a bicycle
- Getting off a bike facing down a slope typically is done by leaving it in gear which keeps the back wheel locked
- OP is correct that some forethought is required on very steep or highly cambered surfaces when leaving a bike to ensure it is stable on the side stand
Do you know how motorcycles solve this problem? Don't do it! Just don't get into that situation. How do you do a hill start? You don't. If you're really forced, you can try, it'll be difficult but often it's just easier to avoid the situation.