Re: OK, I'll bite
The problem is NOT the OS. It's the CPU not functioning as documented, i.e. NOT accessing memory in which the page table says "do not access it", even if it does so only briefly.
While Meltdown does involve speculative access across privilege levels, Spectre does not. And if you believe either of the attacks violates something in the CPU specification, I'd like to see a citation. CPU specifications tend to be quite vague and leave a great deal of room for the implementation.
In particular, memory-protection features are described in terms of their direct effects on registers and memory, not on microarchitectural features such as the caches. There's no magical guarantee that memory protection prevents ever loading anything from an unpermitted page into a CPU storage area that's not directly accessible by the executing program.
What you wish CPUs would do, and what they're documented as doing, are two different things.