BMC alum here – I’ve never heard anything about BMC not having access to their own grades before the end of the semester, that certainly was not the case when I was a student. BMC does have a strong culture of not being competitive with others about grades, or about grade-grubbing – the culture is about doing your own personal best. The Honor Code, like at Haverford, creates a culture of mutual respect and accountability, but I’ve never heard anything about Honor Code and students not being able to access their own grades during the semester.
If you have a source for that, I would call Admissions or the Dean of Students office to ask about it.