Well, yeah. There’s no package police that’ll stop you from installing malware. The argument has never revolved around that; the argument is solely that cooldowns are effective if you use them, and timely detection by third parties is strong evidence of that.
I gave Shai Hulud as an example above. If you want precise timeline examples that demonstrate the efficacy of cooldowns, here’s some examples I collected last year[1].
(See the “Window of opportunity” column in the table.)