I enjoy the debate and seeing the different opinions on the Civil War. I just wish this debate had been triggered by a better article.
Your first statement of his argument (to put a name to your complaint) points out that he is advancing what I think debaters would call a syllogistic error, specifically the error called an "illicit minor": the subject of his major conclusion (about the Civil War) talks about all of the Lincolnian cause, but the premise (about the Cherokee declaration) only mentions one case in point.
Your second statement, of the form of the original poster's error, I think is of the form of a category error, specifically an error of composition, in which specific characteristics (hair) of a part of something (Bob) are sufficient to assign him to a category (cow).
If anything, the obvious omission of pertinent prior events makes the argument even weaker and therefore undermines his position somewhat.
You are now accusing him of an inductive error, either hasty generalization (the experience of the Oklahoma Indians with Federal policy is too narrow to generalize about federal policy) or else unrepresentative sample, i.e. the policies being complained about in the Indian declaration are unrepresentative of the policies of the federal government as a whole.
Picking two whole sources and quoting one document that supports his position while flatly ignoring anything that doesn't support his position or may call it into question in the least smacks of Democratic candidate methodology.
You're describing another inductive fallacy now -- exclusion (picking your data).
Seems you have a few complaints with the post!!
;^)