Hm, it may well have something to do with it but it is not the end of the story.
For the Human (since I have played them mostly and noted their chances):
Probable - Ackdarian, Atuuk, Ketarov, Kiadian, Securan, Shandar, Teekan, Ugnari
Possible - Quameno, Zenox
Unlikely - Wekkarus
Most Unlikely - Boskharan, Dhayut, Gizurean, Haakonish, Ikkuro, Mortalen, Naxillan, Sluken
It is likely that 'Possible' for instance represents a range of numerical values (just as for reputation)
If the bias is zero then the chance (for Human) can be anywhere from Probable (e.g., Atuuk) to Most Unlikely (e.g., Ikkuro). Certainly that is enough to tell me that the bias chart is not sufficient for what I want. It also says that since the bias chart represents numerical values something else impinges other than bias (although I have myself thought that bias may well play a role).