A rigorous psychometric assessment didn't stop a medical services helicopter pilot in JAR-land flying his aircraft under a bridge for kicks, crashing and killing one of his crew. Or the crew of the Puma accident in the media lately flying like dickheads (and who presumably passed similar RAF tests). So how valid, objective and reliable can such methods be?
Somebody instructed and authorised the pilot who lost control at Shobdon. If his attitudes were assessed by several people to be hazardous, how did he get to solo/pass LST/SFH? People instructing, examining and chartering out aircraft also need to assess risk and STOP someone flying if necessary.