Apart from whether or not GMO's are healthy we general believe that customers should get information about products that they want to have. We don't allow artificial diamonds to be sold as naturally mined diamonds, even when De Beers doesn't have an argument that artifical diamonds are unsafe.
I generally agree with your position, but let me be the devil's advocate here:
Let's assume that some fraction of the population are Nazis, and they decide to boycott all Jewish products. Let's assume there is a general agreement on the definition of "Jewish products" (for example anything produced by a company with a Jewish owner, or using such component). The Nazis express a desire to have all products clearly labeled. Would you support this specific customer right?
Basically: How does one pursue the truth when direct engagement with evidence is infeasible?
I came to this question while discussing GMO labeling. In this case I am obviously not in a position to experiment for myself, but furthermore: I do not have the time to build up the bank of background understanding to engage vigorously with the study results themselves. I can look at them with a decent secondary education's understanding of experimental method, genetics, and biology, but that is the extent of it.
In this situation I usually find myself reduced to weighing the proclamations of authorities: