When searching to see the supported SASL mechanisms after running your command I see:
ldapsearch -h 172.16.0.9 -p 7389 -x -b "" -s base -LLL supportedSASLMechanisms
dn:
supportedSASLMechanisms: GSSAPI
supportedSASLMechanisms: GSS-SPNEGO
ldapsearch -h 172.16.0.9 -p 389 -x -b "" -s base -LLL supportedSASLMechanisms
dn:
supportedSASLMechanisms: GSS-SPNEGO
supportedSASLMechanisms: GSSAPI
supportedSASLMechanisms: NTLM