Wait, why not? Knowing who votes for what content, when, and in coordination with whom else seems like it would be extremely useful indeed! Aren't techniques like this already used by FBI etc on Twitter when investigating illegal content and coordination of its' dissemination? Bot networks are taken down on Twitter and other sites all the time using voting data.
Social voting data is a rather sizable and useful dataset for surveillance agencies. HN has a high concentration of current-high-impact and future-high-impact individuals and is therefore a reasonably interesting trove of information.
I realize all this is indeed tinfoil-hat-ish stuff. But I'd be shocked in NSA/CIA/FBI etc was disinterested in online social voting habits of users.
Also, you latched on to a single example I gave. HN may have your email address privately (if you gave it to them) and they also have your IP/access logs. This is all stuff that they save but is not publicly available information.
I'm sure there's more as well. It's not just "internet points" and reducing the discussion down to simply dismissing a single one of my thoughts isn't going to get us anywhere.