I don't think this is necessarily an appeal to authority, for two reasons.

First, because some people will treat that authorship credit as a warning label rather than authority; that would make it ad hominem, not appeal to authority.

Second, because it actually gives useful context to some parts of this spec: "Oh, it makes sense that the author of a language without integer types would propose a spec that claims you don't need integer types". That's not a logical fallacy at all; that's perfectly reasonable reasoning.

I read it as a simple statement of fact. Not an argument for or against anything.

"An appeal to authority is an argument from the fact that a person judged to be an authority affirms a proposition to the claim that the proposition is true."

I don't think the person you replied to was claiming that DEC64 was good or bad because it was written by Crockford? Didn't feel like he was passing any judgement, merely pointing out who the author was...

Rightly or wrongly, Crockford is seen as somewhat of a "god" among the JavaScript crowd, due to his "JavaScript: The Good Parts" book and his work on JSON. Within that crowd, he's seen to posses an extremely high amount of authority. So I think that many of them would see this other work as superior based on his involvement alone, without investigating the ideas and proposals themselves any further.

Ha—I think it's relevant information because it tells me to discount his ideas about numeric types in programming. An Appeal to Lack of Authority.

Providing additional information about the author is a logical fallacy now?

Also, see: http://www.logicalfallacies.info/relevance/fallacists/

It doesn't logically follow that it is good because an authority has created it. But it definitely gives us an information gain, in the information theory sense.

I never said anything about the quality of the initiative, but I think it is worth noting the author. It does give some context.