It seems likely that the reason is that some intel customers are willing to pai a significant premium for the feature and intel doesn't want it to be available for cheap
If what they’ve done with ECC memory is any indication, this sort of market segmentation would only slow down or even kill adoption of AVX-512 in the consumer sphere. Welp, at least there’s no reliability issue here, so Torvalds is unlikely to get angry anytime soon.
Probably intel doesn't care about AVX-512 in the consumer sphere.