Hi Zuma,
I'd recommend using apply_filters in the autoAddGallery function...do it after:
if($psoptions['auto_add']){
//add this
$display_gallery = apply_filters( 'bwbps_gallery_exit', true );
if( !$display_gallery ){ return $content; }
If you use the code above, I'll see if it works and put that apply_filters into the core so you don't lose your fix on the next upgrade. I haven't tested, so don't know if that works or not.
Next, you'll need a filter function (which you can set up in your own plugin or in your theme's function.php file, you can use the is_category conditional: http://codex.wordpress.org/Function_Reference/is_category
Your filter function would need to determine whether it's the right category or not...then return true or false.
Hope that helps,
Byron