I’ve spent time writing CPU detection code for previous projects, and there is nothing that jumps out at me as biased in the linked ISA check. In fact that is really the bare minimum required to split the AVX variants, and will detect AMD support just the same as Intel.

You can compare it to other detection functions - one relatively easy to read, non-vendor biased example that does dig into all the extensions is this Go implementation (not mine): https://github.com/klauspost/cpuid/blob/master/cpuid.go