All Canadian federal budgets for more than 20 years now have included a fair bit of "sandbagging"; make the numbers worse at the start of the year so you can "surprise" with better numbers at the end of the year.  Even without using lowered expectations on economic growth you can be certain that the government will have other elements in the budget, such as the "Contingency Fund", that exist purely to make the numbers look worse just in case the economy worsens during the year.