I've been part of a European startup that added offices in Asia and the US, and we initially always partnered with local companies to do this. It's mutually beneficial. It allowed us to grow more quickly, and it allowed them to make relatively easy money (and, in our case, to dump some of their shittier employees on us without us knowing).

In Proton's case, they already knew each other because Tesonet had previously offered to provide infrastructure during a DDoS attack against Proton.

So maybe it's a conspiracy, or maybe it's just how things go. You can make up your own mind, but you should provide the facts when you make sinister insinuations.