Should relook at this. Original reason for not doing this was that we did not want to ship a win64 version of the SunPKCS11 provider because we did not have access to any PKCS#11 implementation to test with. We did not want to ship something that could not be tested at all and could potentially be DOA.
Are there 64-bit windows providers we can test with now?
An OpenJDK user knows of a potential 64-bit windows HSM that might be willing to provide a PKCS11 library for us to test. See comments for more info.