PAF
Surely it doesn't take a rocket scientist to work out it is further to fly from SY-MC than CB-SY? Having said that, a quick search on Webjet shows the cheapest flight with JQ for SY-MC is $79 and QF for CB-SY around $110.
Perhaps someone thought you may need the extra exercise lugging your bags to reduce the "Russell Office spread".
By all means fly with Virgin - I'm sure the "peasants" would enjoy the reduced whine in the cabin.