In macOS Sierra, the net-snmp runtime libraries are linked to a system private copy of LibreSSL, but MongoDB has a runtime dependency on the system copy of OpenSSL libcrypto. This means that it is impossible to safely load the SNMP support libraries into the same address space as the SSL enabled enterprise build.
The only apparent solution is to disable SNMP support for OS X enterprise builds (including retroactively withdrawing support for the feature on MongoDB 3.2 and 3.4).
If we find that support for this feature is widely needed, we may be able to re-introduce it by vendoring our own copy of net-snmp. However, it is unclear how much use the SNMP support gets on OS X, since it is not widely used as a production database server platform.