The problem worth micro kernels is that abstraction isn’t free. That’s less of an issue with modern hardware running modern work loads because you’d need to put that memory safety in regardless of the kernel architecture and chips these days are fast enough that the benefits of security and safety far far outweigh the deminishing cost in performance. However on the N64 you don’t need any of the benefits that a micro kernel offers while you do need to preserve as many clock cycles as you can. So a micro kernel isn’t well suited for that specific domain. The case would be different again for any modern low footprint hardware because they’d still be running on CPUs clocked at an order of magnitude more and modern embedded system might need to take security or stability concerns more seriously than an air gapped 90s game console.
In short, micro kernels are the future but the N64, being a retro system, needs an approach from the past.
This is why it doesn’t help how modern and 90s hardware have been conflated as equivalent throughout this discussion.