I don't understand what olympus is and how does it work. Is it basically a node that you connect to and it opens channels to other nodes you want to open channels to? If it works tjat way it still has the problem that it is centralized (if you only oprn a channel with them and not anyone else). 

 No, they open channel with whoever they want, the same as you. You open channels with whoever you want. And you have full custody of your money, regardless on whom you open a channel with.
There is no centralization here.