>> If, as you claim, Marc was one of many students, then >> he was improperly crediting the work as that of himself >> and one other.

I don't know what email you're reading but the one I'm reading just has him and one other guy signing off indicating they're members of a group; nowhere does it say they're the only members, or the most important members, or the members who did most of the work, or anything other than 2 people looking for feed back.

Let's say you got an email from "Sue" from Apple requesting feedback on your recent iPhone purchase. Does that imply that since sue works for Apple and she signed off on the email, Sue is the most important person at Apple, responsible for most the important parts of their more successful projects?

No, of course not.