Because (per the article) the metabolism doing the worm is not the roundworm's but the microbe. Which means that the human gut only has to be provide a viable environment for the microbe to do what it wants to do.

This is different, say, than translating the safety or efficacy of a vaccine on a maurine model since the data on the safety and efficacy of the vaccine is specifically for a rodent's immune system.

Common ancestor with potentially a similar gut. That is not definitive against.

The researchers have shown an unexpected effect. They do not know the pathway. The fact the effect exists indicates there is some biochemistry at play that we did not expect to see. What that mechanism is, is not known. So, it is just a question mark, science does not know - and that is simply where we are. We don't know, and we don't even know the chances of the result carrying over to humans. It seems like science needs to identify the mechanism behind this result,then we can start looking at whether that mechanism also exists in humans and also if it functions in a similar way. We might have an enzyme that enhances the effect, or contrary, or not at all. Bottom line, no data is available to make any statements regarding human efficacy, it is a big fat - we do not know

They’re both sort of wet tubes

Probably more similar than not haha

My point is that my biome doesn't have to be at all similar to get the benefit.

All my biome has to do is provide a viable environment for the microbes that actually do the work.

That's not that hard, or wouldn't be if our diets weren't chock full of moieties that kill or damage or modify microbes