Actually, I never said the lily pad in the second scenario is 1 square foot. My starting assumption is that it covers the pond in 30 days rather than the size of the lily pad. In math terms, scenario 1 sets the initial condition and solves for t (time). Scenario 2 sets t (time) and solves for the initial condition.
I thought that might be confusing when I wrote it. That is, that the assumption from scenario 1 would implicitly carry over to scenario 2 but I went ahead because I didn't think anyone would do the math even if they erroneously started with the 1 square foot assumption in scenario 2. You did.
I should probably change it to avoid the confusion.
Yes I would change it a bit to show the intention of 3 days versus the imagined 1 ft starting size.
Other than that good article!