Public ridicule is sometimes a good tool to move people into action. Sometime not the best approach, but, it's funny for those who dedicate their lives to doing this kind of work.
In the security community there's a pretty deep-rooted sense of humor towards "unexpected enlightenment". It's not really directed at anybody - It's mostly directed towards the mindset or theme of ignorance.
His writings do carry a condescending tone, with a faint "l33t hax0r" taste. I think it might be a case of a sudden fame multiplied by the teen spirit :)
I hear from a source very high up in PayPal that a large part of their codebase is evolving at this point and that in the next couple months, we should be seeing a wide range of developer-friendly changes. I'm not advocating PayPal nor do I have any financial interest in PayPal, just pointing out that they acknowledge how far behind they are and desperately trying to catch up.
When you're the market leader, you have to work twice as hard as the next guy in line. Paypal has at least 2 companies plus Bitcoin threatening to replace them at any given moment.
PayPal doesn't have to worry about being replaced as much as it has to worry about being marginalized. If a developer who has never integrated payment into their app asks me what platform to use, I'm going to answer "Stripe" without hesitation because they make it very simple for developers to use. PayPal needs to shift its focus toward making the developer experience better, because right now their documentation is a steaming pile of shit and their web interface is unintuitive.
Also, I really dislike how he handles his disclosures.