[ShockWave512]

В доке адобовской совсем по другому передаются параметры:

var nativeProcessStartupInfo:NativeProcessStartupInfo = new NativeProcessStartupInfo();
var file:File = File.applicationDirectory.resolvePath("test.py");
nativeProcessStartupInfo.executable = file;
 
var processArgs:Vector.<String> = new Vector.<String>();
processArgs[0] = "foo";
nativeProcessStartupInfo.arguments = processArgs;
 
process = new NativeProcess();
process.start(nativeProcessStartupInfo);