Does D2L have a way for the instructor to access my submission while it appears "unread"?
I don't know about D2L specifically, but some software can have issues with properly recording whether some has been read. It is possible for example with some systems that if someone has Javascript not enabled they may be able to  read a file without getting recorded as accessed. 

That said, if this isn't happening, the best thing may be to talk to Department Chair, and ask them to keep your concern anonymous. This will help minimize the chance of blowback/retaliation to you since the individual will not know you were the one who complained.  It may also make sense for similar reasons to wait until the end of the semester before talking to the Chair.