I think most opponents of C++ for OS kernel development take their position because the simplicity of C results allows for pretty straightforward and direct reasoning about the static (asm, obj layout) and dynamic properties (memory allocations, procedure invocation, etc) of their code.

Both C++ and our tooling has come a long way — not to mention a change in the nature of the challenges of kernel development/performance. I think most of the old arguments against C++ have lost their edge.