Why would a car stall in reverse?
This happened to me on a 1986 cutlass 2.5. A wire was shorting out going to the map sensor and only did it in reverse. The bracket on the alternator had rubbed a hole and only grounded when the motor moved, when placed in reverse. I fixed it temporary with electrical tape.
How would you get your car in and out of your driveway? How would you get out of a parking stall unless you pulled through and there was no curb or car blocking you? It is not uncommon to find yourself in a tight area where all you can do is reverse to get out while driving. I would say it is not safe.
If you mean each time you engage car in any gear forward or reverse & it immediately stalls - you have a bad torque converter. Start engine, put foot on brake, put car in NEUTRAL, if it DOES NOT stall, but it does stall if you repeat this test when you put car in drive or reverse = bad torque converter - It's called a "stall test"