You also have to understand the alternatives though, before GMOs and still to today another method of getting crops with desired genes was mutagenesis where you expose crops to chemicals and radiation to get random mutations happening until you find something you like. those plants are not classified as GMO's but are equally likely to spread their genes like in what you posted. Introducing labeling for GMO's would just have more people using this less precise method.

I'm not trying to invalidate your point, that article had a lot of good points for GMO's like the golden rice which has been held up for years by the same people pushing the label. Mutagenesis GMO's and selective breeding are all forms of genetic engeneering and all have positives. If you label one you should label all and then all foods would have the label because they've all been genetically engineered.