As the premise 4 is valid (being the direct deduction of the first three premises), the premise five (5) must be valid too.
Premise five --- the Chinese character system can be mastered in 90 days for anyone who knows not a single Chinese character at the beginning.
Furthermore, the premise five can actually be tested, and such a test was done with the case study data reviewed by,
1. Many American Universities --- data available at http://www.chineseetymology.com/letters.php
2. Taiwan Government --- data available at http://www.chineseetymology.com/taiwan.php
Tienzen (Jeh-Tween) Gong