This is great advice. Also can help to deflect "so and so computer shop does a good job with that sort of thing" if you don't want the work/don't have time/etc.
Even when running my own successful contract IT business, I used to do this sort of thing whenever I didn't feel like taking on a particular job. It also has the side benefit of if the advice you gave was good, then you've helped an ally in the industry (network building), and you've helped out a potential future customer. They'll remember that you're the one who sent them to the folks who solved their issue for them, especially if you sent them to someone who charges a fair price and does good work.