Pottsy, in actual fact you will not be missing your flight because you can't board a flight which no longer exists due to cancellation. The real problem here for you is that RJ doesn't have a suitable alternative until 2 days later. Even non OW alternate airlines have no direct flights for the date you are booked to travel.
My experience is that where a OWA is disrupted for whatever reason beyond the passenger's control (weather / mechanical / cancellation), there is never any suggestion the rest of the itinerary is at risk.
This is the relevant rule:
14.3.9 If a Member fails to board a Flight Segment of an itinerary containing only Classic Award Flight Segments, the remaining Segments will be cancelled. The cancelled Segments will only be reinstated if Classic Award seats are available. If any Segments are reinstated, the Reinstatement Fee will apply (see the
Fee Schedule). In addition the Points required for the entire Itinerary including both travelled and reinstated Segments will be recalculated and any additional Points required will be deducted from the Member's account.
