Dolphin is a rare case where open source has benefited a project as delicate. Look at Pj64, it went open source and there is not a dream team that has improved emulation as rapidly. It is rare to find an open source so organized and goal orientated.
However, its was quite some time before N64 emulators went open source that popularity of the emulators dropped. Hard to say if there is a lot of interest in DreamCast emulation.
I coped the Project from 2 years ago to Github, so the source is available.

Just not the current version.