Re: Consensus is not science
"When you hear consensus remember that this means that it is an opinion that cannot be backed up by an experiment i.e. it is a hypothesis rather than a theory."
I do not think that word means what you think it means.
"Consensus" means there's general agreement over some issue, no more and no less. Why there's agreement is a different issue - it might be because people have just assumed things without actually investigating, it might be a working hypothesis, but it might also be because the investigations have been done and everyone got the same result.
To extend one of your examples, the consensus is now that heavy and light objects fall at the same speed [in a vacuum]. And that is very much not an opinion that cannot be backed up by experiment.
So, your subject is correct; consensus is not science, but at the same time it's also not a indication that something's only a hypothesis.