In the second sentence, the student states that if Vallejo is correct, there is insufficient evidence for claiming that glass-blowing originated in Egypt.
However, in the conclusion the student incorrectly infers that to mean glass-blowing must have originated elsewhere.
According to the passage, Vallejo only claims there is insufficient evidence for determining glass-blowing originated in Egypt, not that there is evidence that glass-blowing did not originate in Egypt, or that there is evidence that glass-blowing originated elsewhere.
The fault in this passageís reasoning is similar to fault in this more simple passage:
Although most scientists believe that cigarettes cause cancer, a new study by Scientist X questions the validity of the evidence linking cigarettes to cancer. Therefore, if Scientist X is correct, cigarettes donít cause cancer.
Kohsuen, hope this helps.