The proper response to ignorance is education not hiding relevant information.
The proper response to dangerous food ingredients is to ban their use, not to label them as dangerous.
Prove that RR Maize is dangerous, and the FDA won't mandate a label saying "Warning, this food contains RR Maize and may cause your toddler to explode"; They will simply ban it from being used at all.
Labelling is for hazards that only threaten a specific and identified minority - such as allergy sufferers - who need to be warned of something that is harmless to the general population.
Peanuts are harmless, except to the minority of people who are allergic to peanuts.
By all means, if you can identify a minority of people who are susceptible to harm from a specific GMO, then label products containing that GMO - but if you can't, then labelling is a red herring. Either a given GMO is universally harmful, and should be banned; or it is harmless, and no additional labelling is needed; or it is harmful only to an identified minority, in which case, you must be able to point to the human characteristic that renders a given GMO dangerous for that minority.
A food label that says 'May contain peanuts' is useful. A food label that says 'May contain plant or animal products' is not - because it is too broad to help anyone avoid a particular risk. A food label that says 'Toxic - do not eat' is pointless, because food that can reasonably be labelled in that way shouldn't be labelled - it should be banned.
GMOs are clearly not generally toxic (or most of the US population would be sick or dead). So the only reason they might need to be labelled is if there is an identifiable minority who can be harmed by them.
Please feel free to identify that minority, or STFU about labelling.