They (Docker) might not be. Docker Hub is their turf, they can do whatever they want (and face the consequences).
However, the post doesn't say that LinuxServer want free service. They say that they had the opportunity, and they try every year. From what I read, they're perfectly fine with a "No, you are not selected this year".
Being decent and being interested in giving a free service are mutually exclusive. You can provide free service while being mean, you can deny people from your free service while being polite.
The people who wrote this post is only interested with the "polite" part. So, they can see what they're at and act accordingly (reapply, pay, or find other alternatives).
Requesting communication is not a bad thing.
