Probably because they see it as a weaponization of the justice department. Several of the indictments are using novel legal theories, and the timing coincides with Trump's reelection campaign.
ISIS probably isn't the best example, because promoting terrorism and advocating violence isn't protected free speech. Regardless, I don't think this would apply to a politician making a general statement like this, but government agencies working behind closed doors to suppress legal content.
Title is a bit disingenuous, the ruling actually says they are prohibited
from even talking to social media companies with “the purpose of urging, encouraging, pressuring, or inducing in any manner the removal, deletion, suppression, or reduction of content containing protected free speech.”
Government should not be cohering social media companies to silence speech, this seems fine to me.