Repulsive at -9 is just not right. Repulsive at -6 vanilla works out to 13.5 in Ice and it was easily the worst pick in vanilla.
Value of Repulsive in a single player game depends on how you approach the game. MOO2 a.i. is quite weak in many ways and a.i. is quick to close treaties, and can easily be manipulated. One example I have given on the Civ forum that by 'saying hello' you can already manipulate a.i. behaviour. Because of this a SP game quickly becomes dull. Imo, a SP game can be interesting if you treat a.i. as you would treat a human player in a 1-1: as your enemy. And thus Repulsive is a default pick to take. Of course Repulsive could have been valued at -10 or lower, but that would only make the game easier so what is the point in it?
The reason I have chosen 45 picks is because I have considered race constructions, for example the classic UniTol,P+1,LHW or UniAqua,P+2,LRHW both cost 45 picks. So if for example p+1 is valued +7 instead of 6, then the effect for the various races need to be evaluated and a need could arrise to increase the total available picks. The reason you need many negatives picks to construct a race in ice, instead of just -12 or -10 picks is to have the player start with more disadvantage.
Lastly, the 'multiples of 3 system' was recently introduced and I think it works quite well, within the current picks balance. If there was a need to revalue for example Feudal to -8 and Low-G to -14, then if necessary I would adjust the other negatives as well to preserve the possibility of combinations to get to a certain negative value (currently at -21). In other words, 'multiples of 3' is not a goal in itself, it is simply one of the elements of valuation to make some interesting race constructions possible.