Yes, BazisLib fully supports writing kernel-mode drivers and even has several examples of compact and efficient object-oriented drivers.
The discussion about “only C” is caused by the fact that misuse of C features would cause one write more lines, but misuse of C++ features causes one source line generate much more binary code (e.g. use of implicit std::string constructor from a constant string, when not needed), that results performance drop not noticeable by developer directly. That’s why, rather than carefully design C++ programs and check the result in disassembler for some cases, many developers prefer using “old plain C”.