Yes, but there's no ad hominem in explaining to someone that historical comments were downvoted because of specific flaws.

Sigh, I'll have to quote myself again: "involve pointing out factual but ostensible character flaws or actions which are irrelevant to the opponent's argument."(emphasis mine)

It is ad hominem because it is completely irrelevant to my arguments. I might have been downvoted years ago by making wrong claims about Teddy Bear, so what? Why would you want to bring that up in a discussion?

How come you even knew about my other comments in the past? Is it because you are a long time member here and remember past discussions and remember what I wrote in them? Maybe this is what caused you to argue based on the past history, based on what you knew about me and my past comments instead of sticking to the present comment and facts stated therein. If you argued based on what you knew about me, e.g. past comments, other than the one that was specifically mentioned this constitutes an ad hominem in the latin sense (meaning directed towards the person). You didn't manage to stick to what was written but brought in your personal judgment about me about other comments I have written in the past. And that is totally irrelevant to my point. I've never claimed that all my comments in the past were correct. So other comments of mine in the past, be they correct or wrong are totally irrelevant to the point in question. I was very careful in choosing one specific comment which doesn't even contain a single word of mine. I said this 3 times at least now. I was making my point with this comment, why couldn't you stick to that one? We are now writing a lot of words that have nothing to do with my argument.

Btw, to make it simpler imagine that the Roland of today is another person than the Roland who wrote the past comments, lets call him "RolandPast". Now I'll paraphrase you: "RolandPast got downvoted repeatedly because RolandPast made claims that were demonstrably extremely unlikely and hist attempts to marshal evidence for his claims relied on very poor fact checking. Downvoting for such reasons isn't "scientific fraud."

I hope this makes things clearer. If not, I'll paraphrase again this time using "X":

"X got downvoted repeatedly because X made claims that were demonstrably extremely unlikely and his attempts to marshal evidence for hist claims relied on very poor fact checking. Downvoting for such reasons isn't "scientific fraud."

ad hominem abusive is only a fallacy in the limited sense that there's an implicit "and therefore the argument is wrong" attached to it.

No, on the contrary, read the wikipedia section.: "This tactic is logically fallacious because insults and even true negative facts about the opponent's personal character have nothing to do with the logical merits of the opponent's arguments or assertions."

So it seems that you are the one who missed it in two levels at least.