An interesting point, and one that demands the attention of "Mr. Logic." ;)
In truth, the article posted is wrong on this point, as far as it goes. The appeal to authority (argument ad verecundiam) is really only a logical fallacy when it is an appeal to an inappropriate authority. It is perfectly legitimate for me to cite Doctor Stochastic (and you) as authorities on the mathematics of radiometric dating, assuming I examine your credentials and find you to be bona-fide experts in this matter. This does not mean that you must be correct, of course - even experts are mistaken or wrong sometimes.
The logical fallacy arises, as I said, when we make the inappropriate appeal to authority. For example, assuming for a moment that you are an expert on the mathematics of radiometric dating, it would be inappropriate to cite your opinions on, say, constitutional law, and to then give those opinions undue weight based on your expertise in some other field. You are, of course, entitled to your opinions about constitutional law, but as a non-expert in that field, your opinions have no more weight than those of any other non-constitutional law scholar.
But, if we were to rule out this sort of argument entirely, we might as well stop discussing much of anything, since virtually no-one is a bona-fide expert in everything. Since we are fairly specialized these days, we must be permitted to refer to the arguments and logic and conclusions of experts in fields outside our own. It is still incumbent upon us all to examine the credibility of experts, and to examine arguments for obvious logical flaws, of course, but beyond that, all of us have little choice but to accept the conclusions of actual experts in some fields - which fields those are will vary from person to person, naturally.
No kidding! Did you notice that the first time you read it? Or was it only after I showed how it would make hypocrites out of most of us?
It is perfectly legitimate for me to cite Doctor Stochastic (and you) as authorities on the mathematics of radiometric dating, assuming I examine your credentials and find you to be bona-fide experts in this matter.
Um, how would I present my credentials for your examination? As far as that goes, how have your other "authorities" done it? Bio data on the flyleaf of their books? I guess I've done about that well in a previous post...
Mankind has built elaborate social institutions to try to ensure that experts are properly certified. In fact, one of them has "certified" me (in math, anyway). The same institutions teach us that it is a logical fallacy to appeal to inappropriate authorities. The subtext tells me that "inappropriate" refers to "uncertified"—by those institutions, at least. How surprising.
Would Srinivasa Ramanujan have been considered an "appropriate" authority in mathematics? How much weight should we give to the degree he was finally awarded? Should it bother us that some of his results were wrong? On the other hand, should we ignore his brilliant accomplishments?
The real problem with the "appeal to authority fallacy" is the question of "appropriate authority." Who decides? Reasonable people will often disagree on who is the "authority" on an issue.