Hi Yesidid,
#1:
According to the Society's interpretation of Matthew 24:45-47* Jesus would have based his decision to appoint the Society only on what they had been teaching down till 1919. That's why Franz said "as of 1919." Therefore, whatever they were teaching after 1919 (no matter how false it was) would not have entered into his decision in 1919.
Witnesses have been trained to automatically apply Proverbs 4:18's "old light" to all of the Society's pre-1919 teachings that were not true. But it doesn't register with them that those teachings were not considered as old light in 1918-1919. And something else they don't think about is that the time to pass an examination is when it is given, not several years (sometimes decades) after the exam is over. And the Society says that Jesus' exam was over in the spring of 1919.
#2:
Personally I feel that there was one teaching in particular that would have gotten Jesus' attention. If in 1918 he had asked the question "Who really is the faithful and discreet slave?" (Matthew 24:45)* they would have answered according to what they believed: "Charles Taze Russell." And so according to what they teach today, the Society would have failed that most important question.
How faithful or discreet could the Society have been when it is realized that God didn't let them know (1) that his Son had returned in 1914 (assuming he did return in that year), nor (2) who his Son's "slave" was?
According to their interpretation of Matthew 24:45-47*, in the spring of 1919 Jesus was saying to them, "You are my faithful and discreet slave." But according to their actual history they were saying, "We are not your faithful and discreet slave."
If Jesus did in fact try to appoint Rutherford and his associates "over all his belongings" in 1919, they would have rejected his offer because they believed that Russell had already received that appointment.
The Point: The only way the Society even has a chance of being "God's organization" today is if what went on in their history actually happened according to their interpretation of Matthew 24:45-47.* But since their history and their interpretation do not agree on such critical matters (and the other pre-1919 teachings already mentioned on this thread), this is why Ray Franz and many others feel that it would be an insult to Christ Jesus to say that he was so pleased with what they had been teaching as of 1919 that he gave them the awesome appointment mentioned in verse 47.
_____________________
* Here is their interpretation of Matthew 24:45-47 as it appears on page 24 of the January 15, 2008 Watchtower:
"When Christ inspected the faithful and discreet slave' in 1918, he found those anointed ones on earth to be faithful in providing spiritual 'food at the proper time.' Hence, Jesus was pleased thereafter to appoint them 'over all his belongings .' (Read Matthew 24:45-47)"
Don Cameron