There was a certain rich man, which was clothed in purple and fine linen, and fared sumptuously every day: And there was a certain beggar named Lazarus, which was laid at his gate, full of sores, And desiring to be fed with the crumbs which fell from the rich man's table: moreover the dogs came and licked his sores. And it came to pass, that the beggar died, and was carried by the angels into Abraham's bosom: the rich man also died, and was buried; and in hell he lift up his eyes, being in torments, and seeth Abraham afar off, and Lazarus in his bosom.
And he cried and said, Father Abraham, have mercy on me, and send Lazarus, that he may dip the tip of his finger in water, and cool my tongue; for I am tormented in this flame. But Abraham said, Son, remember that thou in thy lifetime receivedst thy good things, and likewise Lazarus evil things: but now he is comforted, and thou art tormented. And beside all this, between us and you there is a great gulf fixed: so that they which would pass from hence to you cannot; neither can they pass to us, that would come from thence. Then he said, I pray thee therefore, father, that thou wouldest send him to my father's house: For I have five brethren; that he may testify unto them, lest they also come into this place of torment. Abraham saith unto him, They have Moses and the prophets; let them hear them. And he said, Nay, father Abraham: but if one went unto them from the dead, they will repent. And he said unto him, If they hear not Moses and the prophets, neither will they be persuaded, though one rose from the dead.
Who then is a faithful and wise servant, whom his lord hath made ruler over his household, to give them meat in due season? Blessed is that servant, whom his lord when he cometh shall find so doing. Verily I say unto you, That he shall make him ruler over all his goods.
I can't speak for the WTBTS, but scriptural exegesis normally favors those who are doing the interpreting. In Luke, most would argue that Jesus never gave a parable that wasn't, in many ways, true to life. In the allegory that Luke gives, a man who had thought of nothing but himself on earth found himself entreating the righeous Lazarus, who had died and now sat in the bosom of Abraham. It's a compelling story about a man who failed to keep his first estate and was forced to beg for mercy from a man whom he had held in disdain during life.
Then in Matthew, the Lord is speaking of his own coming in the latter days. Those who are prepared for his coming will be those he rewards. Thus it is, he will reward his faithful and wise servant who he finds doing his will. A few things here:
- the servant will be of the Lord's authorized household
- he will be the ruler over his household
- he will feed and care for the rest of the staff
- that servant will be exalted to being a ruler over all things
The GB cannot be this servant because, like the first parable, not a prophecy of future events. It's a teaching aid.
The "faithful and wise" servant is not self-appointed or self-acclaimed, but is of the Lord's authorized household and the Lord must recognize his servants, for it is his household.
Because it is not a prophecy, the parable explains the rewards of those authorized servants who prepare themselvs for the Lord's coming by serving others; for the greatest man in the Lord's house is the greatest servant. In the time before the Lord's arrival, that servant who is busy serving others will be exalted by the Lord at his coming. In other words, the Lord's servants who prepare for their Lord's coming and are not found sleeping shall be rewarded. It's not "one" servant, but many; for it applies to all of the Lord's servants who await his coming.