I'm guessing it's a moot point. If the OP has dust covers then a chainring bolt spanner ring tool (or something similar) will work. Since the OP simply wants to remove the crank to access the the bottom bracket, there would be no need to remove the self extracting crank bolts lock rings, as the OP would simply use the extracting crank bolts to remove the crank. However, if the OP doesn't have a spanner to remove the dust covers, your tool would also work for that application; and it doesn't tend to bugger up the holes the way the chainring tool does.