So if there was another crew member in the flight deck, then they would have been able to stop that moron from parking the Airbus on the side of the Alps..
No, they aren't saying it
would have stopped it, they are saying it
might have stopped it.
The report also points out however that introducing another crew member onto the flight deck may increase the risk of causing another incident or accident (FWIW one of the BEA spokesmen also said the same and provided a bit more detail during a Press conference when the report was released). In short by insisting on a "two person" rule to try and solve problem A (in this case pilot suicide) you may be increasing the risk of loss of life in the future caused by B, C D, etc happening ....I'm not going to spell out all the B, C or D's in plain language here but one look round your airline might give you some some ideas.
The level of extra risk is considered to vary from airline to airline which is why the EASA recommendations allow airlines to carry out their own risk assesment before deciding whether to implement a two pilot rule, or an EASA approved equivalent measure which is more appropriate to their operation.