I believe the complaint here is actually more "The ACLU is no longer defending my political enemies".

The issue is not that the ACLU is taking on causes the author disagrees with. The issue is that the ACLU has switched away from "I disapprove of what you say, but I will defend to the death your right to say it" thinking. And instead they are taking a few cases of "I disapprove of what you say and will therefore not defend you". Let alone the weird Heard case that seems to be "You give me money so I give you backing and legitimacy".