You are selecting the nurbsCurve
shapes, but your animation is on the transform
# list the shape nodes
nurbsShapes = maya.cmds.listRelatives(curSel, allDescendents=True, noIntermediate=True, fullPath=True, type="nurbsCurve", path=True)
# list the transform nodes to each shape node
nurbsTransforms = maya.cmds.listRelatives(nurbsShapes, type='transform', parent=True)
# select the transform nodes
cmds.select(nurbsTransforms)