She already had passed the time frame for that, was not in default for her previous sponsorship, and was deemed eligible to sponsor again, both legally and in terms of being in a position to assume responsibility for this undertaking. That was already determined.
However it seems to have created a bias against the couple, which in conjunction with the red flags they have that are a common characteristic of marriage fraud for North Africa (age and culture in particular), seems to have affected the decision, regardless of all the proof of genuine relationship they submitted up front and in the interview.
Really though the age gap isn't that huge and 36 is hardly a grandma! Canadian women have access to great health care, have money to spend on beauty products, vitamins, creams, lotions, potions. Healthy living and physical activity (gym, yoga, sports, dogwalking, etc...) is part of the lifestyle here which helps with preservation and slower aging when compared with a woman of the same age living in harsher conditions in a country like Morocco where those activities are not commonly partaken by women. A 36 year old Canuck can be quite hot and seem a lot younger in comparison.
Not to mention times have changed a lot in terms of technology bringing people together and open mindedness regarding mixed marriages, and what was once seen as culturally abnormal or unusual is now quite common and not such a big deal.
By all means, weed out the obviously fraudulent cases and we don't know all the details of what went exactly on with this one. But unless he grossly underperformed in his interview, which does not sound at all like the case, this appears to be a very unfair decision that was made in advance. If applicants pass all eligibility and legal/security criteria, the only basis for decision should be whether it is a genuine relationship or not. Personal opinions on whether or not the couple should be together, past failed relationships, etc.. should not be used as a means to penalize.
In any case, she is lucky in that she is in a position to go and live with her husband while either appealing or reapplying which should make the next year or two more bearable and in doing so should strengthen their case for the future.