On what the website is saying; one can talk of the strength of an inductive argument, where induction is Humean style induction. And I think the referenced site is doings so. For example, an inductive argument that goes from “apple 1, 2, and 3 are green” to “all apples are green” is stronger than one that goes from “apple 1 and 2 are green” to the same conclusion. The use of an absolute “strong” and “weak” by the website is a little odd, however.
Note that “strong” can be used to talk about logics, and about (inductive) arguments, and the usages don’t line up in an obvious way. A strong logic is one that gets more out of less, whereas a strong argument is one that uses more to get to the same place. And “strong” as used by the website, on my reading, applies to an argument.