I've managed to get Void working on my G5, and frankly, modern Firefox is painfully slow. Now, it could just be because of bugs, but these forks of FF are a wonderful thing, because they can bring the current web to much older hardware. They perform better, and they don't need to be 64-bit.
So I figure, if it doesn't hurt to keep on porting forks of Firefox that work on 32-bit hardware, why not keep it up? After all, the G5 is the only on that runs 64-bit code, and a slow G5 isn't much faster than a fast G4.