OpenGL a bloat??? It's around since Windows 3.1 in the mid 90s and runs on every CPU integrated graphics of the last 15 years. It is multiplatform compatible and much faster than software renderer. The problem is more that it's outdated and may be dropped first by Apple, I guess.
Isn't it a bit to early to ask for the engine to get open source? Maybe it has no negative effect to the sales but it's very unusual for a new game with no team and intention like a system port.