We agree with these two commentators [one of whom, William Safire]. We have seen that there is no clear basis for the "rule" at all [a common conclusion]. We suggest that you follow the writers rather than the critics: writers use enormity with a richness and subtlety that the critics have failed to take account of. The stigmatized sense is entirely standard and has been for more than a century and a half.
My purpose in this post is more to call attention to the work cited than to engage in the dispute. I haven't yet summoned sufficient interest to read the full entry.