Of course, given that it's a one-person project, chances are the code is relatively small and approachable. I think you are much more likely to be able to easily support modify a one-person project than something bigger.
Now, clearly, supporting the code yourself will not always be an option or a good choice; it's just much more likely to be viable with a one-person project.
I agree, though you need to be careful to make sure you could maintain the project if needed, even though ideally you'll never have to, and you need to check that before you make use of it in anything important.
Many complaints about open source projects that go stagnant are due to people not doing this, and being stuck using something they can't enhance/fix because they don't have (and can't afford to buy) the expertise.
Now, clearly, supporting the code yourself will not always be an option or a good choice; it's just much more likely to be viable with a one-person project.