karen davis was photographed on google street view flashing her breasts .
she handed herself in after reported by police with disorderly behaviour .
south australian law professor says oral swab test was unnecessary .
professor rick sarre also believed ms davis should not be charged .
police said her ` actions were the same as someone flashing their genitals '
sa country town mum hit back at critics saying they are insecure .
she plans to do a topless skydive for her 40th birthday next year .