I'd prefer if he just give his address, but in Dan's defence he does offer some pretty clear hints in his profile page: "Email is my full name @ gmail." https://news.ycombinator.com/user?id=luu
His email address is also given prominently on his linked resume: https://github.com/danluu/tex-resume (periods are optional in Gmail addresses)
http://danluu.com/about/
This is especially strange as the author then mentions email there, without providing an actual email address:
| Please ping me on twitter if it looks like your email got eaten by my spam filter
Maybe the author expects a reader to brute-force lots of addresses "something [at] danluu.com"?