If you clear out the various multi-platform work for OpenSSL, _of course_ it can progress more quickly and more securely. The multi-platform work is where so much of the work has been done.
As a person making their living writing software for MacOS X and iOS, do I care about this code running in MacOS 9? I don't care one bit. They explain it very well: You don't need to be "multi-platform" if you are standard. Instead of "we have thirteen implementions of SSL_memcpy that run on a dozen completely outdated platforms that nobody cares about", they use memcpy and say "if your platform doesn't support a standard C function correctly, fuck you and your platform". Which is the correct approach.
A slightly more pragmatic approach is to keep those implementations, at least the most crucial ones, but please make sure that you use memcpy etc directly on any sane modern platform.