I think the one flame would be insufficient to raise the whole surface of the spilled oil to its flash point. I will have to try something. This is why I tried it using a bowl because of the low center of gravity.
Candles don't get left unattended or near other easily combustible material.
In a SHTF situation, nost if the time will be in near dark because I know my house better than any intruder would. One little candle light in a central location of the place will help with some tasks that would need accomplishing.