Author of curl and libcurl denied entry to U.S. with no explanation
gizmodo.com
gizmodo.com
Here's a guess: some blacklisted piece of software uses curl and credited "daniel@haxx.se" as required by its licence[1]. Daniel was then mistaken as a creator of that software, and his email address flagged for any ESTA applications that use it.
edit: apparently I'm not the first to think this: https://news.ycombinator.com/item?id=14643525
Obviously immigration should do a better job on their false positive rates, and not just their false negative rates, but these are never going to go to zero. Someone probably made a clear mistake in this particular case, but without details who knows. For all we know there's some social media or blog post of his with something like a joke about harming he-who-shall-not-be-named.
I've been reading it as “Steinberg” all this time. Oops.