I agree with the overall sentiment of your statement. I think people have blown this situation far out of proportion. People touting their model is broken or that the company is going to fail over this one inciden... Same with Dropbox. It does have something to do with their successes.
That said:
People attacked the founders because, for better or worse, they got directly involved in this. And if one of the co-founders really did tell her to take down that blog post to make sure their valuation doesn't take a hit, that'll draw a lot of ire.
Plus, Airbnb has millions of dollars. They have the PR capacity to deal with these scenarios. If they aren't framing their true side of the story, whose fault is that? Like it or not, people are going to speculate especially when there is a long history of corporations side-stepping responsibility. (I am not at all suggesting that Airbnb is not trying to help. I'm saying why I can see how people can assume the worst) The fact that PG has to publicly defend them is ludicrous. It's like a father defending a fully-grown son.
The core issue here beyond the Dropbox security folly and the previous Craigslist/Airbnb debacle (which both sparked a ton of vitriol) is that this exact scenario this woman went through was bound to happen and should not have gotten out of hand. Credit cards get stolen. The process is: phone a 24-hotline, cancel a card, get a new one in the mail, challenge the fees, hopefully get money back. With this Airbnb scenario, the woman had to contact Airbnb through a freelancer who worked for them because no one initially responded to her e-mails or phone calls!
Craigslist does a very good job of warning people of the dangers all across the process. If you click on sublets, there are huge links at the top warning of fraud, scams, and personal safety tips. If you click on a post, there is a giant yellow box that warns the user of scams. On Airbnb: Nothing on the homepage, nothing on the lists of properties, and nothing on the listing itself. Airbnb isn't liable for the damages (as stated by their agreement) but they should have made more of an effort to educate the users of the potential hazards of the site and liabilities for the buyer. Hell, I used Airbnb in Paris and I genuinely thought that Airbnb would have a very responsive team in case shit hit the fan. With Craigslist, there is no false sense of security: every step of the way, they warn you.
The whole situation far bigger than it needed to be.