I'm also far behind on literature, but do not see big problems with such a hypothesis. Accepting the possibility large azhdharchids did not fly (hypothesis which I do not dare to support or refuse to support because of ignorance) I also think that all flight specializations may be just explained by descent from volant ancestors, and not usefulness in the actual giant.
Ohhhh no. Have you seen a azhdarchid humerus? Or coracoid?
-- Palaontography: http://palaeo.jconway.co.uk