The tone of this article is really strange. It somehow sounds like the author is upset that someone forked his project. (There are several indicators of that throughout the post.) That's the whole point of free software. If you didn't want that, you shouldn't have chosen a free software license.
Also, as explained in other comments, it's unlikely this is actually a fork of curl. It's more likely it's just a wrapper around winhttp with a curl-like API.
He got an email requesting support for software with the same name as his, that points to his documentation, while having zero access to the software itself. I'd say being mildly annoyed at that is warranted, especially since we're talking about a gigantic corporation on the other side.
This isn't even the first time[1] Microsoft has done something like this with the curl name. And, then as now, people bother Daniel with support requests.
Also, as explained in other comments, it's unlikely this is actually a fork of curl. It's more likely it's just a wrapper around winhttp with a curl-like API.