I think Carter actually made the original fud dice:

I forgot about that. The irony!

In the context of my post, I am asking whether we should make some effort to appease the people who are actually fudding even when they are actually fudding.

Fair. In that case, my answer is: no. "We" (the royal we) should meet legitimate critiques with well-reasoned responses. If "we" don't find the critique legitimate, there's not much use in responding to it -- it's not going to convince the FUDder, since (by definition) they're engaging in bad faith; and for the audience who may be reading, such engagement countenances the original bad-faith argument.

Also I don't really think the definition of fud has changed: it's in the same set of words as terrorist and troll and as such it's always a little bit of rhetoric, it's wordy weapon to dismiss people.

We appear to disagree on this point: once upon a time, my sense is that one could raise concerns that were viewed as actual concerns to be considered; the response was to consider them and (perhaps) counter them. Now, raising concerns is met with accusations of bad faith; and usually, idiotic personal slander and fourth-grade histrionics. That seems different and (relatively) new. (But, as mentioned elsewhere, perhaps I'm doing what everyone does, and remembering a past that was better than it was.)

I'd wager that every legitimate threat has been called fud over the years, as have many illegitimate threats.

That it assuredly true.