They don't run the social network, they run part of it, lemmy.ml.
Which you actually are federated to in kbin.social just like I am at lemmy.world. Meaning you interact with their users and communities.
This is the whole point of fediverse, nobody exclusively runs it and gets to do whatever the fuck they want with it. They can do whatever they want on their part of the network but if it starts affecting other parts (instances like lemmy.world) they can just cut them off without losing any functionality.
I also expect many many more people contributing to the development of this project as it picks up users. It's necessary, not for political reasons but because the original development team is actually pretty small.