It means you can use them as a hobbiest or a student. For example, you can now use Rider as the IDE on an Open Source project.

If you are writing code that you are going to be paid for, you are supposed to pay.

Of course, they know a lot of small devs will use it that should not. But few of them would have paid anyway and this creates a much greater pool of buyers when those devs get jobs or achieve commercial success.

I am a Rider fan so this is exciting.