Do you think someone smart would invest in a project that depends 100% of a closed group of people? So, if Serena and CaptainDero stop their activity the code will be not longer maintained thus the token living inside the blockchain would end up not valuable at all.
Agree on this point. There's loads of examples where the original devs got tied up in another project/new job and had to drop their cryptocurrency project. Following this on open source coins the community can pick up development, sometimes to greater success than the original team. It is a great way to ensure future-proofing and availability of the currency. Why not open for external review (will make the code better undoubtedly) and allow faster iteration through PRs and community engagement.
Code is open for external review. The source code isn't out on the alpha only. You can see the rest of the code and compile yourself. You just can't use it freely for your own project.
edit : Funny how the "angry free software" guys come out every time dero releases something new or proves it's resilience to attacks.
edit 2 : If the devs abandon the project, then that would be valid to say they need to make it free software for it to survive.