the Mother of Believers

when you get passed what the "age requirement" is supposed to mean and is a principle for—instead of acting like it's some necessary number of the universe for life to exist—and you outline all of the criteria expected for a "lawful union" (criteria that are only broadly knowable from limited natural epistemology—so broad on aspects essential for living and society that it indicates the need for guidance to precisely discern all of the criteria), and then examine the union especially by the moral principles established broadly and internally, you can only conclude that the union was lawful.

so then, instead of some arbitrary age that you're presenting as an issue from hearsay, when you're discussing a point in time (that you have no study on, no sincere concern for, nor can you even name a book on the biography of the subjects) when calendars were not the norm, nor was literacy except a new affair...
tell me, is your issue still present if:
A) the wife was emotionally & mentally prepared and consenting
B) the wife was physically prepared and never harmed
C) the wife was even previously engaged via previous bethrothal
D) the wife's parents were consenting
E) the culture of the people regarded it as normalcy and the wife of age
F) the rate of development in the climate of Arabia over 1400 was not identical to that of today
G) the wife considered her husband to have been the best spouse and never complained
H) the husband did not marry her for immediate intimacy but that did not occur until later with all of the above assured?

i'm trying to understand exactly what your issue is, because scholars have various ages for her, and we don't know what it was exactly, with some scholars presenting better evidence pointing to approximately 19 years of age. ex. she was even on battlefields, battlefields have age limits and don't allow minors of such an age