This has nothing to do about ageism. This applies to any person of any age who has ego big enough to think that their knowledge of industry is relevant after they take prolonged break and be socially inept enough to brag about how they are still "in".

I don't disagree with your point about fundamentals, but in an industry where there seems to be new JS framework any time somebody sneezes - latest tools are very much relevant too. And of course the big thing is language changes. The events I'm describing happened in the late 00s-early 10s. When language updates picked up steam: Python, JS, PHP, C++. Somebody who used C++ 98 can't claim to have up to date knowledge in C++ in 2015.

So to answer your question - people were laughing at his ego, not the fact that he didn't know some hot new framework.