AB knew there would be backlash, they just underestimated the magnitude. Other companies, like Ulta, had marketed with Mulvaney and faced backlash, but survived. Even though AB now seems to be blaming an outside marketing agency for the can, it still had to be approved.
It's easy in hindsight to say this was a bad decision. But they were simply trying to market their beer to the 4 million or so people who follow Mulvaney's social media account, and the other people who have given her video series over 1 Billion views. They figured there would be backlash but that it was worth the risk.
I really don't know what's wrong with marketing your product to a pro-trans demographic. The only message they are sending is inclusivity.
And the kicker is, unless you follow Mulvaney on social media, you never would have known about the sponsorship...but Tucker Carlson, Kid Rock, etc al. decided to quit complaining about the Green M&M not being sexy enough, and jump on board the latest outrage.
I don't drink lite beers and hardly any other AB products, so I don't care if they are boycotted. I also had never heard of Dylan Mulvaney before this started. I just don't understand the outrage over marketing to trans people. Would you get upset if they marketed to other groups you find bothersome....like Disney fans?