The NP-hard property allows you to reduce any problem in NP to it.
As you stated it, generalizing (or reducing) 3-SAT to another problem proves nothing and is a common mistake for undergraduates learning complexity theory (reducing the wrong way).
To say you generalize an NP problem isn't even a statement that typechecks in the language of complexity.
Reduction on the other hand, is a formally defined term and is very specific in what it means exactly.
If moultano had actually said 'generalize [the problem]' then I wouldn't have even left a comment, because everything you have said is correct, I just don't think his statement needed that clarification. Now, however, I'm interested in whether the word 'generalize' can be used with respect to algorithms. (<--- someone not in complexity theory)