I don't have a problem with the 'two organs making one' framing. The fact that they are 'symbiotic' now doesn't change that. In fact it helps me understand two key facts. One can't grow out of the other, and they work differently. Great

The Portuguese Man o’ War[0] is a symbiotic organism. If you want to get technical, I guess we are, as well. We’re really kind of fascinating meatbags.

[0] https://en.wikipedia.org/wiki/Portuguese_man_o%27_war

We are absolutely symbiotic from our cells upward. A large percentage of your body mass is bacteria, including the symbiotic bacteria you feed in your gut with the food you think you’re eating only for yourself.

Recent research has suggested that viruses supply us with a second immune system. These viruses keep down the numbers of bacteria and other microbes in our gut etc

We are so used to reading negative things about viruses that it makes a change to find out how they can benefit us too.