any event fear of > 90% of humans dying by 2100 is far from the only possible reason to oppose GMOs.

I didn't advocate that it's the only reason. That's why I asked for a more precise question.

I took "bioengineered" to imply 'deliberately' and "pandemic" to imply 'contagious',

If the tools that you need to genmanipulate organisms are widely available it's much easier to deliberately produce a pandemic.

It's possible to make a bacteria immune to antibiotica by just giving them antibiotica and making not manipulating the genes directly. On the other hand I think that people fear bioengineered pandemics because they expect stronger capabilities in regards to manipulating organisms in the future.