Good principles remain good regardless of exceptional circumstances.
> needed to change or else they collapse and don't function at all
Yeah, they changed _and_ they don't function at all. Now they just protect the causes their donors agree with while retaining the prestige of the name.
Personally I think a total collapse would have been preferable.
The ACLU didn't get anyone killed, violent right-wing individuals did. The right to have a political protest rally is enshrined in the Constitution.
Consider the looting and rioting that took place following the George Floyd protests. It would be absurd to suggest that because violence and crime was happening at some of these events, the political speech they represented might not be worth protecting.
As a result, going to bat for the Unite the Right rally in 2017 was a massive misstep and resulted in them losing a large amount of donors and professionals working for them. Naturally they would've needed to change or else they collapse and don't function at all.