From the homepage it sounds like they've prioritised geometry fidelity for CV research rather than performance:
Infinigen is optimized for computer vision research, particularly 3D vision. Infinigen does not use bump/normal-maps, full-transparency, or other techniques which fake geometric detail. All fine details of geometry from Infinigen are real, ensuring accurate 3D ground truth.
So I suspect the assets wouldn't be particularly optimised for video games. Perhaps a good starting point though!