That's not about "not being ready", the GPU really doesn't care whether the numbers it is multiplying are coefficients of a matrix or a bivector.
The problem is that all libraries, drivers, etc. use matrices, quaternions and vectors. So you would have to constantly convert back and forth, which is both error-prone and a non-trivial performance problem.
Of course, you could build your own libraries for everything, but that's just crazy. Who has time for doing that?
Not to mention that writing a mathematical library like that is a highly non-trivial task. Not just the algebra part but also numerical stability and accuracy are a big deal. That requires a very skilled person, naive implementations will rapidly blow up in your face.
And doing all this what for, exactly? So that the GA explanation of rotations doesn't require 4 dimensions while the math complexity of rotor algebra ends up being the same as with quaternions? So there isn't really a performance benefit neither.
Who has time for that? Me. And, presumably, Marc ten Bosch. When you want to make a game that uses full 4D graphics, existing libraries just don't cut it, and writing GPU code to understand arbitrary-dimensional rotors is worth it.
The problem is that all libraries, drivers, etc. use matrices, quaternions and vectors. So you would have to constantly convert back and forth, which is both error-prone and a non-trivial performance problem.
Of course, you could build your own libraries for everything, but that's just crazy. Who has time for doing that?
Not to mention that writing a mathematical library like that is a highly non-trivial task. Not just the algebra part but also numerical stability and accuracy are a big deal. That requires a very skilled person, naive implementations will rapidly blow up in your face.
And doing all this what for, exactly? So that the GA explanation of rotations doesn't require 4 dimensions while the math complexity of rotor algebra ends up being the same as with quaternions? So there isn't really a performance benefit neither.