Maybe you're right but this is how I read it.
Alice's writing is not strong -> Alice did not attend college.
therefore
Bob's writing is strong -> Bob did attend college.
On the other hand, what the other user deducted was:
* If you attend college -> You probably end up writing properly
* OP doesn't write properly -> He probably didn't attend college
Which is a proper logical deduction rule called modus tollens. https://en.wikipedia.org/wiki/Modus_tollens
Maybe you're right but this is how I read it.
Alice's writing is not strong -> Alice did not attend college.
therefore
Bob's writing is strong -> Bob did attend college.