If a project refuses to make their code open source we shouldn't be delegating to them. Simple as that. Open source code and blockchain/decentralization go hand in hand.
You know, that doesn't sit well with many people, but its hard to argue against that logic.
And that is totally understandable, because people have been living under the shadow of artificial scarcity and competition their whole lives.
The idea of making our projects open source is frightening... because how can we make sure our ideas don't get stolen and we get paid? If we were living in abundance we wouldn't have to worry about such trifles.