For a very brief time, "doxing" (that is, dropping dox, that is, dropping docs, or documents) used to mean something useful. You gathered information that was not out in public, for example by talking to people or by stealing it, and put it out in the open.
It's very silly to talk about doxing when all someone has done is gather information anyone else can equally easily obtain, just given enough patience and time, especially when it's information the person in question put out there themselves. If it doesn't take any special skills or connections to obtain the information, but only the inclination to actually perform the research on publicly available data, I don't see what has been done that is unethical.
Call it stalking or harrasment if you prefer. Regardless its rude (sometimes illegal) behaviour.
That's no justification for using visitors to your site to do a DDOS.
In the slang of reddit: ESH
It's neither of those. Stalking refers to persistent, unwanted, one-sided interactions with a person such as following, surveilling, calling, or sending messages or gifts. Investigating a person's past or identity doesn't involve any interaction with the physical person. Harassment is persistent attempts to interact with someone after having been asked to stop. Again, an investigation doesn't require any form of interaction.