If you do as said you will expose the base metal of the connector and cause additional accelerated corosion.
Also dielectric grease is an insulater and has no place on the contact points of a connector. Maybe the connector will displace the greese, but you can float a battle ship in a 1 molecule thick sheet of water. To think that the grease will be fully displaced probably will not happen
Dammit! I just got done doing this with my American Automotive bulkhead. I swear it was in the instructions. GAH!!! Ill have to check. I could swear they also said to seal the outside with something....Now I am questioning my existence altogether!