I like Rachel G’s suggestion Mrs. Ellison is making the best of defeat (:D) but you make a great point that in Ch. 30 she does not sound like she is speaking of a match she objected to. Perhaps Mrs. Ellison, like the Dashwoods, was not overly concerned with Willoughby’s financial situation. Mrs. Dashwood is uninfluenced by material considerations: “It was contrary to every doctrine of hers [Mrs. Dashwood’s], that difference of fortune should keep any couple asunder who were attracted by resemblance of disposition” (Ch. 3). Mrs. Ellison may think along these lines or perhaps not even know of Willoughby’s troubles. It could be that Willoughby did not complain of poverty to an heiress and her family as he did to the Dashwoods who live on a restricted budget themselves. It is also a good point Willoughby carefully avoided the words love, engagement, and marriage—I do not know how it slipped my mind. Perhaps what happened and I like this better than the financial angle, is Willoughby’s behavior towards Miss Grey was so that she and all her friends thought they were engaged but as with Marianne he never actually committed to it:

"I [Marianne] felt myself," she added, "to be as solemnly engaged to him, as if the strictest legal covenant had bound us to each other." (Ch. 29)

But for this strange kind of secrecy maintained by them relative to their engagement, which in fact concealed nothing at all, she [Elinor] could not account… (Ch. 14)

" I [Mrs. Dashwood] should never deserve her confidence again, after forcing from her a confession of what is meant at present to be unacknowledged to any one. (Ch. 16)

Lastly, Mrs. Jennings—dear woman:

"Law, my dear! Don't pretend to defend him. No positive engagement indeed! after taking her all over Allenham House, and fixing on the very rooms they were to live in hereafter!" (Ch. 30)