There is so little known about him besides family stories and what his sons and daughters (my boyfriends father, aunts, and uncles) have in their heads.
One cannot put a lot of credibility in what people have in their heads. They are based on perceptions of a specific event in time, as they interpret it. An example:
When I was 11 and my brother was 6, we went on a vacation to the Lake of the Ozarks. At a recent family gathering, he said, I still remember the time you tried to drown me. He believed that for over 50 years. In reality, he didn't know how to swim then and I had just learned that year. He would jump off the back of the dock and could dog paddle just enough to go 5 feet or so until he could stand on the bottom. Then he decided to jump off the front of the dock, which was 12 feet farther out. He couldn't make it back and started to drown. I jumped in and floundered us both to shore and saved his life. In his mind, he only remembered the drowning part with me holding him across his chest.
Events are only snapshots in time based on the individual perceptions of the people involved. A researcher can only record them. Their credibility may be suspect.
And some of what I have come across is quite wrong. Like when i replied to that one post on here about the urine comment. That offended my boyfriends father quite a bit.
I laid that groundwork to say this. At the time of the incident mentioned, your boyfriend's father was but a young lad. Youth are not always privy to things that their elders do. The person who made that posting related a personal, 1st person event that he experienced. He is a highly respected, professional researcher and noted author in the muzzleloading field and was a friend of Mr. Sutter. He has no reason to fabricate rumors of events he experienced personally. Rumors grow, not from events themselves, but by those who repeat the story with their own embellishements, and grow exponentially as they are passed on over the years.
If you aspire to be a "serious" researcher, then you must learn to set aside the bias of others. That is why researchers seek to record 1st person events, because secondary and tertiary sources often contain biased perceptions or interpretations. Thus, you cannot allow the indignancy of your boyfriend's father influence anything you might seek to record.