[seL4] When is seL4 not a good choice?

Are there any kinds of OSs for which seL4 is not a good basis, at least for now? I am mostly looking for features that can’t be implemented in userspace, and which seL4 isn’t likely to get any time soon (if ever). Things that come to mind are NUMA, EFI variables, and scaling to systems with thousands of cores. I hope I am not badgering the developers with questions. I am merely an interested bystander. Sincerely, Demi