How to prevent jumping off held object?

How to prevent jumping off the object I'm holding? I can just put it under my feet and abuse it to multi-jump. Should I turn off collisions for player or the solid object? (but then the object won't do physics checks for the other physical objects and walls) And I want to be able to jump off mid-air objects that don't fall but just hang in air, like RC planes. I'm using the default FPS controller and this pickup/holding code on Unity 5.

 var normalCollisionCount = 1;
  var spring = 50.0;
  var damper = 5.0;
  var drag = 10.0;
  var angularDrag = 5.0;
  var distance = 0.2;
  var throwForce = 500;
  var throwRange = 1000;
  var attachToCenterOfMass = false;
   
  private var springJoint : SpringJoint;
   
  function Update ()
  {
      // Make sure the user pressed the mouse down
      if (!Input.GetMouseButtonDown (0))
          return;
   
      var mainCamera = FindCamera();
   
      // We need to actually hit an object
      var hit : RaycastHit;
      if (!Physics.Raycast(mainCamera.ScreenPointToRay(Input.mousePosition),  hit, 100))
          return;
      // We need to hit a rigidbody that is not kinematic
      if (!hit.rigidbody || hit.rigidbody.isKinematic)
          return;
   
      if (!springJoint)
      {
          var go = new GameObject("Rigidbody dragger");
          var body : Rigidbody = go.AddComponent.<Rigidbody>() as Rigidbody;
          springJoint = go.AddComponent.<SpringJoint>();
          body.isKinematic = true;
      }
   
      springJoint.transform.position = hit.point;
      if (attachToCenterOfMass)
      {
          var anchor = transform.TransformDirection(hit.rigidbody.centerOfMass) + hit.rigidbody.transform.position;
          anchor = springJoint.transform.InverseTransformPoint(anchor);
          springJoint.anchor = anchor;
      }
      else
      {
          springJoint.anchor = Vector3.zero;
      }
   
      springJoint.spring = spring;
      springJoint.damper = damper;
      springJoint.maxDistance = distance;
      springJoint.connectedBody = hit.rigidbody;
   
      StartCoroutine ("DragObject", hit.distance);
  }
   
  function DragObject (distance : float)
  {
      var oldDrag = springJoint.connectedBody.drag;
      var oldAngularDrag = springJoint.connectedBody.angularDrag;
      springJoint.connectedBody.drag = drag;
      springJoint.connectedBody.angularDrag = angularDrag;
      var mainCamera = FindCamera();
      while (Input.GetMouseButton (0))
      {
          var ray = mainCamera.ScreenPointToRay (Input.mousePosition);
          springJoint.transform.position = ray.GetPoint(distance);
          yield;
   
          if (Input.GetMouseButton (1)){
              springJoint.connectedBody.AddExplosionForce(throwForce,mainCamera.transform.position,throwRange);
              springJoint.connectedBody.drag = oldDrag;
              springJoint.connectedBody.angularDrag = oldAngularDrag;
              springJoint.connectedBody = null;
          }
      }
      if (springJoint.connectedBody)
      {
          springJoint.connectedBody.drag = oldDrag;
          springJoint.connectedBody.angularDrag = oldAngularDrag;
          springJoint.connectedBody = null;
      }
  }
   
  function FindCamera ()
  {
      if (GetComponent.<Camera>())
          return GetComponent.<Camera>();
      else
          return Camera.main;
  }