The problem is that while they say do no harm that is not what they actually do.
In Ireland a scientist figured out how to make regular potatoes immune to blight by taking some genes from wild potatoes and inserting them in the kind we eat. The atni GMO crowd managed to kill any kind of testing of that and instead potatoes are still done using the "normal organic methods" of killing blight on potatoes which is to put heavy metals on them. So safety is clearly not the issue and can't even be studied.
Actually the whole cross breading thing overall is pretty screwed up in many cases. Farmers discovered natural thing they could put on plants to increase the chance of cross breeds working. It turns that that nearly all of them are chemical mutagens and are FAR more dangerous than precise genetic engineering is.
I am not saying that we should blindly trust GMO or Organic stuff. What we need to do is fully allow the scientific development and analysis to see what truly works for us for safety, nutrition and environmental damage. Right now though that is not what is happening and decisions are made based on fear.
What I do want to see is all products on the market should have their full DNA mapped out and put online in a searchable data base (BLAST) and that includes all the ingredients that go into your product along with any other chemical species in there we know of. Then you would have an app on your phone and could select what you are allergic to, what you don't want in your food etc and then scan a tag on the food and your phone would tell you if it is safe for you. Right now there are thousands of food allergies and we only list about 20 or so on food. This anti-GMO stance I see now does not help knowledge or safety in any way it is just fear.
I want to see actual information on food and people able to make real choices. So long as this is just fear based that will not happen.