This is a new feature that discourse has added. It’s called slow mode. It’s main purpose is to promote thoughtful discussion in fast moving or contentious discussions. When enabled, users must wait before posting again in this topic.
This thread in particular has caused some contention in the recruitment category. As such, we have tried to limit the frequency of new posts. I have modified the period as 24 hours does seem a bit excessive. Hope this clarifies what happened.