If I accurately understand the recon-all script, then -noaseg sets UseAseg=0, but "autorecon2-noaseg" is a different flag, which only sets the following things.
case "-autorecon2-cp": case "-autorecon2-noaseg": case "-autorecon2-wm": set DoNormalization2 = 1; set DoSegmentation = 1; set DoFill = 1; set DoTessellate = 1; set DoSmooth1 = 1; set DoInflate1 = 1; set DoQSphere = 1; set DoFix = 1; set DoMaskBFS = 1; set DoWhiteSurfs = 1; set DoSmooth2 = 1; set DoInflate2 = 1; set DoSegStats = 0; set DoCurvStats = 1; breaksw
Best Regards,
Gabor