Get unused influences via OM2 and remove them using cmds

Maya_RemoveUnusedInfluencesOM2.py

import maya.cmds as cmds
import maya.api.OpenMaya as om2
import maya.api.OpenMayaAnim as omAnim2

def getSkinCluster():
    sel = om2.MGlobal.getActiveSelectionList()
    shapeDagPath = sel.getDagPath(0).extendToShape()
    shapeMeshFn = om2.MFnMesh(shapeDagPath)

    inMeshPlug = shapeMeshFn.findPlug('inMesh', False)
    conn = inMeshPlug.connectedTo(True, False)
    if len(conn) < 1:
        print "No skin cluster found on the shape node!"
        return False
    
    connPlug = conn[0]

    connNode = connPlug.node()
    isSkinCluster = connNode.hasFn(om2.MFn.kSkinClusterFilter)
    skinClstr = omAnim2.MFnSkinCluster(connPlug.node())
    
    return skinClstr

def getUnusedInfluences(skinClstr):
    unusedInfluences = []
    influenceObjs = skinClstr.influenceObjects()
    for each in influenceObjs:
        cmpsDagPath, weights = skinClstr.getPointsAffectedByInfluence(each)
        
        if cmpsDagPath.length() == 0:
            unusedInfluences.append(each)
            
    return unusedInfluences

skinClstr = getSkinCluster()
unusedInfluences = getUnusedInfluences(skinClstr)

for each in unusedInfluences:
    cmds.skinCluster(skinClstr.name(), edit=True, removeInfluence=each.fullPathName())