I think there's an argument to be made that Scientific American shouldn't have opinion pieces that readers will misinterpret as scientific fact.
This would seem to be true if they tend to run opinion pieces that are all from one "side". If they ran pieces that espouse conflicting viewpoints, it would not imply that they support all of the opinion pieces they publish.
From the look of it, they stick to one team. They wouldn't be taking this heat if they had a broader diversity of thought.
I would guess that if you asked 100 random people who had heard of Scientific American, many/most would say that SA publishes science and has no Opinion section. Before this dustup, I would have been in that camp.
It's actually unfortunate if publications decide only to publish things they agree with because that fails to acknowledge they could be wrong.
Evolution and creationism are settled wars (as far as science is concerned) and wouldn't be interesting to readers. It would be interesting to read a serious assessment of, say, the Covid lab leak theory.
Should it be impossible to have a rigorous scientific method for reporting and peer review in the news section, while advocating for certain actions or perspectives in the opinion page?
If someone sends me a Wall Street Journal news article that reports on facts, I can trust it, even if their opinion page is intellectually bankrupt.