But the lawsuit isn't arguing that "companies need to consider the downstream impacts of the things they do."

It seems like it is though? From the text of the article:

These activities pose risks to political stability, public health, and rule of law, threatening the intrinsic value of the global economy and thus the value of diversified portfolios.

The argument they seem to be going after is that we live in a highly connected society and powerful companies with outsized influence can disrupt the global economy which therefore hurts their investments. Whether or not Meta has _actually_ done that is another question, but I think that this line of thinking is interesting.