so really.. why are spouses rejected?

[canadianwoman]

As a minor aside - CIC thought that a five year age difference was a valid reason to reject an application? In normal circumstances tat would seem way too harsh; I'm guessing that they could just tell he was dodgy, and had to find something concrete to state as an objection. What do you think?

Usually a five year age difference is no big deal, even if it is the woman who is older. In India, though, the visa officers are used to dealing with arranged marriages, and would be very suspicious if a man's family agreed to an arranged marriage to an older woman who is disabled and uses a wheelchair. True, this couple met online, but in their cultural context, where most likely the families were heavily involved, it is an unusual marriage.
Lots of appeal cases from India hinge on the fact that the visa officers think in an arranged marriage everything has to be 'normal' and traditional. The man older, but only by a few years; both families involved in the match-making and the wedding; a big ceremony with hundreds of guest; same marital background; both about the same level of education; etc. On appeal, these 'less normal' relationships will often win, but in this case the visa officer was right.