Now they are firmly on the map, which presumably helps with hiring, doing deals, influence. If they stop publishing something, they run the risk of being labelled a one-hit wonder who got lucky.
If they have a reason to believe they can do even better in the near future, releasing current tech might make sense.
What is DeepSeek aiming for if not that, which is currently the only thing they offer that cost money? They claim their own inference endpoints has a cost profit margin of 545%, which might be true or not, but the very fact that they mentioned this at all seems to indicate it is of some importance to them and others.