The linked article is only a few hundred words long. It probably took Daniel half an hour to write. It would take far longer to write, integrate, test, document

The linked article is only a few hundred words long. It probably took Daniel half an hour to write. It would take far longer to write, integrate, test, document, and maintain even a simple easter egg to the same quality standards as the rest of the curl project. That last bit is key - to the same quality standards. curl is a really well-done, carefully-built-and-tested project. If we were talking about most other pieces of software - yes, a small easter egg wouldn't have taken much effort. Not in this case. If someone else had volunteered to take on all of the effort of maintaining the easter egg, Daniel might let it in - but that would still be more work on his part to rope them in to test their thing after every change to code adjacent to the feature. Conversely, nobody prevents you from forking curl and adding the easter egg in yourself. Why don't you?