There are a few events in his life that he shared here and on steam. For example he shared the nature of the job he does, shared the type of equipment he needs for it, shared some other stuff like music interests, etc, mostly on steam. Also the time when he takes off matters, it happened a few times that he took off for a week or two, it maybe possible to match those times with some other local events that are also available in his approximate physical location, that is simply displayed in gameme. Put all those facts together as well as some events, as well as local businesses and local events, as well as times when he's up and times when he's not here and you will have a fine list of people that could match the physical portrait. Exclude the rest by using simple deductions method and you will know who Bison is. The problem is that no one really cares, or has time for this, but you can still try.