Because embedding new species into an untested environment can be devastating. My example is the accidental import of tree snakes to Guam, which resulted in the complete extinction of all birds on the island, because the snakes ate the eggs faster than the birds could adapt. There are numerous numerous other examples of accidental release of animals destroying ecosystems.

There's nothing with GMOs that make them inherently more dangerous in the sense you're discussing, though.

That you know of. Have you vetted these GMOs against all possibilities of people's DNA? Perhaps unreasonable. How about testing against people who are considered "unhealthy" by the trial criteria? Nope, science knows nothing about how GMOs affect those people, yet claims they are safe.

Those things would depend on the organism itself, not whether or not it has been "artificially" genetically modified.

I think there should be a ban on "owning" custom sequences of DNA, as it will eventually lead to an accumulation of most of our "biological capital" in the hands of very few companies, which could then effectively control what and how we eat (and many other things as well). Already now most biodiversity has vanished from agriculture, with only a handful of different crop species accounting for more than 99 % of all harvests. This is highly dangerous economically, politically and environmentally.

I'd argue that what you're talking about isn't really a problem with GMOs so much as a problem with a lack of regulation.

The biggest problem is they're not open source. What went into making that organism? Is there a standard for documenting this and reasonable public disclosure when relevant?

Foods have ingredient lists for a reason.

I'd argue that any organism is inherently open source, just not necessarily free and open source.

By that logic you could argue that software is inherently open source.

As the reverse engineering communities will be glad to tell you, software basically is open source. It must eventually be decoded into instructions to run on a processor, and while it's not impossible to fully sign / encrypt the binary blobs before they are run, it is practically not worried about for most applications. Without using specialized hardware, you can at best obfuscate your code, but you cannot make it impossible to eventually disassemble and understand.

Assume your code will be disassembled at some point by a bad actor. Don't assume that any code distributed to a client is safe or trustworthy, and expect that any data, methods, or secrets contained in that code are now public knowledge. To secure your environment systems under any other assumption is a dangerous falsehood.

If it's been baked the source is wrecked, so not really.

Ending a bash script in rm $1 doesn't magically make it not open source, just inherently self-destructive.