Here, to paraphrase our friend George in Netview support,
are the 4 stages of SNMP security on AIX 4.3.3, bos.net.tcp.client:

1) Off: 4.3.3.0-4.3.3.13
2) On, and no way to turn it off: 4.3.3.14 - 4.3.3.20
3) On by default, but you can turn it off with the -U: 4.3.3.21-4.3.3.27
4) Off by default, but you can turn it on with the -S: 4.3.3.28 and up

I'm glad that's over with....

Cordially,

Leslie A. Clark
IBM Global Services - Systems Mgmt & Networking