I think people on this site are a bit too used to open source projects you can just fork and use based on their license. This is not the case here.

But the voyager dev has not seen or used apollo's code to build voyager. He has done everything from scratch only taking heavy inspiration from Apollo. Christian has helped indirectly by being the one to develop the UI which serves as inspiration but considering that voyager is not a competitor to apollo, in my opinion he has no right to be outraged at the fact that it is a looklike. He is free to not contribute to voyager and it is true that he has already contributed a lot indirectly but him getting angry or upset at the fact that the UI is pretty similar makes no sense to me.