But I don't even understand this. We've seen absolutely nothing of Cole besides they survey, which was clearly incomplete. Our knowledge of DHMG comes from two pieces of concept art and again, this survey which is hardly reliable. The fact that Cole and DHMG's addition to the game would make the gender ratio 6:3 is much more convincing that we won't have both of them than any of this "evidence".
Well, I guess your mileage may vary. For me, it's evidence because it exists. I'm not saying it's the most reliable evidence, but it's there. Particularly for DHMG, who is also in the concept art.
The 6:3 gender ratio isn't evidence at all to me because they've never made any statements either way about the gender ratio. If they had at some point said, "there will be a roughly equal gender ratio" or "there will be a similar gender ratio as past games", then maybe it would be evidence. However, you are assuming that the 6:3 ratio isn't something that they want and then using it as evidence. It doesn't come from them at all though.
Remember that a male mage Hawke had 8 companions (Carver, Aveline, Varric, Anders, Merrill, Isabela, Fenris, and Sebastian) and it was a 5:3 ratio, so that's not too far off. Yes, Carver was only in part of the game, but the Hawke sibling counts, imo, because s/he was in the prologue, act 1, a cameo in act 2, the ending 1/4 of act 3, and both DLCs. Also, Sebastian was DLC, but since there aren't DLC companions in DA: I, he counts in the total pool like the 9 DA: I companions do.