I think activism implies service to an idealistic cause. I don't believe CNN has any idealistic causes, they're a capitalist firm servicing their market.
I don't mean this as a defense of CNN in any way. They're clearly giving their audience what they want to hear which drives revenue, making them more of an entertainment company than a news company. But the problem of for-profit news is bigger than CNN.
I'm not sure we can really separate activism from corporate greed in the context of the media. Typically you have a lot of rank and file journalists and editors who are activist and corporate leadership who have figured out how to monetize their employees ideological fervor. Moreover, as "activists" are rewarded financially for their commitment, they become greedy grifters rather than mere devotees of a toxic ideology (consider prominent activist-grifters such as Kendi or DiAngelo). Which is all to say that it seems not particularly worthwhile to try to distinguish between activists and grifters because it seems more like a spectrum than distinct categories and all positions on the spectrum are pretty equally toxic as far as I can tell (you're either propagating misinformation out of zeal or greed and one doesn't seem strictly better than the other).
I don't mean this as a defense of CNN in any way. They're clearly giving their audience what they want to hear which drives revenue, making them more of an entertainment company than a news company. But the problem of for-profit news is bigger than CNN.