On the other hand, I'm also fairly sure base on some things that I've seen that Eugine has downvoted people while he replies to them as part of an ongoing disagreement(Edit:And he seems to be doing just that to me right now in another conversation, which is sort of amusing at some level.) And this sort of thing seems indicative of the sort of attitude that would be more likely to go and engage in block downvoting.

This is actually what makes it fairly easy for me to believe that Eugine is responsible. In discussions I've had with him in the past, he seems to downvote my comments automatically, without regard for content, merely because I am disagreeing with him. Take, for example, these two comments. Both of them are responses to Eugine, and both of them have exactly one downvote, which I am pretty confident comes from Eugine.

I can't see a legitimate reason for downvoting either of those comments. Neither one makes an argument or presents a controversial opinion. They are just presenting facts, facts which correct some misconception upthread. The fact that they were downvoted seems to me an indication of pretty significant mindkilling. Basically, the downvoter seems to be saying, "I don't want to see politically inconvenient facts on this website." Either that or, "I don't want to see people challenging my political views on this website." That kind of attitude seems quite compatible with indiscriminate bulk downvoting.