This exercise goes to show how poorly worded aviation law really is!!
CAR 233 is referring to the planning stage, so what happens after push back is irrelevant
You could also argue in CAR 234 that reasonable steps were taken to ensure that the aircraft has sufficient fuel. As long as you keep yourself availed of the appropriate weather, and recalculate your fuel on arrival that is considered to be 'reasonable steps' If the forecasts says CAVOK all the way then you get the ATIS and it's broken at 100' you have taken reasonable steps to ensure you have enough fuel. The fact that the TTF changed doesn't make you in breach of those CARS.
Off the top of my head there was a 747 on a domestic flight going to Perth who went past the PNR then the forecast changed to fog. I think they just shot the approach and landed after declaring an emergency.
QF A330 into SYD did the same thing got the latest weather through their descent PNR for Canberra wx was ok for landing. When they contacted approach the aerodrome was fogged in and they autolanded.
There was some other event in Perth 10+ years ago where the wx changed at the last minute and they were tossing up ditching near Rottnest but ended up autolanding. I think that one might be more urban myth than fact though.