Let's not forget that the 413 also has a lot of research that indicates that it is not necessary, and only after the new government came in, did new 'research' come to light...The only reason the greenbelt removals died is because it became a political hot potato with improper political meddling behind it. If the PCs had done a proper process on the removals (i.e. an open call for removal requests, a few months of evaluation, then a removals list) instead of just a bombshell dropping of a list of a select few properties - the decision would still stand.
The 413 is not a political bombshell - quite the contrary - it's a well backed infrastructure project with an immense amount of research, backing of provincial transportation staff, long term infrastructure forecasts indicate its need, etc. The cancellation of the 413 in the Liberal era is the political move - much like the greenbelt removals are the political move in 2023.
The thing is that the PCs with a bit more foresight could have done the greenbelt removals with decent justification and opponents would have had little to stand on. Their rushing of the process, and the improprieties which occurred as a result, instead threaten to take the whole government down. Literally a few extra months of review, a bit of extra staff time, and an open call of removal requests could have completely sidelined the entire scandal - and even if a few developers did have closer-than-they-should relationships with the MMAH, those removals could have been better slipped through with a proper process which didn't raise any eyebrows.