I have found that doing the following seems to prevent version 6261 from being updated: -
Block outbound TCP to external port 443 (i.e. HTTPS) for processes SASERVICE.EXE and SITEADV.EXE.
Set things so that SAREG.EXE and SASYNC.EXE are completely blocked.
I use Agnitum Outpost software firewall which makes it a simple matter to block these processes as described above.
Version 6261 continues to work well without v2.8 spoiling the party. I haven't noticed any attempt to do an update.
"So far so good" the man who jumped off the Empire State Building was heard to say as he passed the 70th floor.