Here's my take on this topic - And though people may work in various ways, I guarantee you this approach works:
That MIDI fader isn't sending out data that you'll find in your track. It's setting a starting volume. Just like the pan pot in that track header/inspector, it won't be adding data to your track unless you arm it for recording automation, and you move the fader or the pan pot.
In the MIDI spec, CC7 isn't meant to be a continuous controller for playing an instrument. It's meant as a general and usually static volume setting - the potential volume of the instrument. You can set up a general MIDI mix by having your instruments at various levels using those MIDI faders. Then you record CC11 to dynamically control the volume of the instruments throughout the tracks. Many synths/samplers change the timbre of an instrument as well as the volume when CC11 is used. CC7 doesn't have that ability.
Some synths, like most freebies, Do have CC7 as the only available volume control, so you record CC7 continuously for volume control on those synths.
Those faders in the track headers control the faders in multi-timbral synths that have mixers, like the ARIA Player that all Garritan Libraries use. The best approach when using ARIA, and other players like that, is to go ahead and let the faders in Sonar have control. Set your potential volume with those faders, and you'll see the player's faders are moving with them. You can turn the Sonar faders off, but why do that? If you ever touch the fader again during your work, that reactivates their control anyway.
You need to have Some kind of starting volume set for your software instruments, and it's best if you have some headroom above that starting level, so Sonar's default of 101 (out of 127 possible levels) is an excellent starting point. Often, you can just leave your faders at that default setting and then rely on your dynamic CC11 performance volume performance to do the rest of the balancing as well.
I generally leave my Sonar MIDI faders at 101, perform the tracks, and then worry about what the balance is between instruments when I move on to mixing the project which I always do with bounced audio tracks. If I didn't bounce to audio, then I'd be more concerned with getting all those faders set at levels that make for a good mix of all the instruments I'm using.
So, the original question was a concern about how to "stop a MIDI track from sending CC7 volume" - and it actually isn't the right thing to be concerned about. You have to have Some initial setting - do it with those Sonar faders, but don't worry about screwing up your tracks - those faders aren't sending out data that ends up in your tracks unless you automate them.
Randy B.