Thirdly, if I wanted to write an automatic down voting script, it would have to download a page from PerlMonks every second to check the new posts by that user.

Nope. There's an irc channel (and quite possibly more than one) which publishes notifications of new posts on PM. Probably also some RSS feeds and other forms of "push" notification as well. So it's not merely possible, but common for a newly-posted node to have actual human eyes reading it within a minute or two of being posted. And posting at 1am in your local timezone doesn't affect that because the PM community is worldwide - your profile says you're in Florida, so your 1am is 9am for me in Scandinavia - and there are surely monks in the US who are routinely at their keyboards until well past 1am.

Of course, the notification feeds would also make it easy for a bot to react "instantly" to new posts, but Occam's razor says that curious (or bored) monks with irc up in another window so that they can immediately read new posts is the more likely explanation, given that those monks are quickly checking out everyone's new posts. Neither bots nor conspiracies targeting you are needed to explain what you've observed.