No Zorba, usually the only thing that delays the SCSI bus check is if it can't find a device it is used to seeing.
I have two identical systems with SCSI, and one is Adaptec 2940UW. The other is SymBios. The Symbios is much faster than the Adaptec in doing that pre-boot inventory and check. I like it to display the devices so I can see if something is amiss. Takes about 10-15 seconds.
Turning off the bus only really affects bootability to a SCSI HDD. The rest of the chain says "life goes on." Ctrl A on boot, Advanced Config, set BIOS to disabled. Or . . . set F6 to Default and it will also be so.