The BGO would not normally see the transcript. The only transcripts I've seen are when I do Senatorial/Congressional Interviews and in those cases they are NEVER on candidates that I am the BGO for.
In general, the BGO interview is to look at things that the Academy Admissions team can't see from the documents that are submitted. They have the actual transcripts, SAT/ACT scores, etc but they can't tell how a candidate studies and how they prioritize activities. They can see if a candidate was a team captain or an Eagle Scout but they can't see what the Team Captain is DOING as captain or what the Eagle Project was, how they did it, etc.
Those are the types of things that the BGO is likely to see as opposed to a C during Freshman Year.