I defer (sic) to A-Floor with respect to the explanation of scene occultation but that written seems perfectly reasonable and clear.
As to the second phrase, "defect deferral" is basically an attempt to use some excuse to delay fixing something that is known to be broken. In other words the operator of an FSTD should not simply hold-off from fixing something simply because it is inconvenient or tricky to take care of it.
- GY