Losing between 25 and 40 million dollars in a legal settlement would be a crippling blow for virtually any company — but for satellite radio giant SiriusXM, which cut such a deal in November after a long battle with pop group The Turtles over pre-1972 royalty payments, it could turn out to be a triumph. For the past eight years SiriusXM has not been paying royalties on the music it plays that …