To me the USG's responsibility is to express those conclusions, and the data to back them up. That's it.
Let me give you a counter example. According to the USG we should all eat a bunch of grains and carbs and avoid fats and especially saturated fat. I'm pretty sure that at least for many of us that is TERRIBLE advice, especially for the half or so of the population with diabetes or pre-diabetes. The evidence to support the US dietary guidelines, at least to the extent they are presented as more or less universal, is weak - that's clear enough.
But the point isn't who is right - I know low carb, high fat works for ME, and I don't care at all how much saturated fat I eat if it's from natural sources our bodies have been using for fuel for 1000s of years. I eat this way and have fairly effortlessly lost 50 lbs and kept it off for over a year now, without trying. The question is whether the government should suppress the alternative to the high carb, grains, etc. diet. I don't think they should. The "truth" in diets is presented as 'objective' but it's in fact quite subjective. I'm fine with the government issuing dietary guidelines as misguided as I think they are, but it's a different ballgame entirely when the keto or LCHF advice out there is suppressed by the government as untrue or lies.
So on your specific question, I believe the data show that ivermectin is pretty useless, if not harmful, but dangerous for us to accept that it's government's job to prohibit that view from being aired. The government is wrong often enough that I don't think they should have the power to suppress information.