I don't work at FD, I can't give you the breakdown of the faction alignment to open numbers. What I do have is experience in open and anecdotal evidence. Also if you check the number of empire aligned groups with a combat leaning you'll see they out number the either the feds or alliance.
I do agree on the fact that there is more empire aligned groups. Now I doubt that there is a real significative difference in the solo/open proportion of those groups in regard of the feds/alliance aligned one's.
Well, without any reliable numbers, my experience in the statistical field tell me to not suppose anything.
My point was just to say that, if it's true that solo players weight more on the community goals than open one's, it is a non issue regarding who will won the CG. Just play the way you want, there are solo player backing your CG side anyway.