I won't defend the cut to the GST, which I always disagreed with. But there's an obvious disconnect here: you can't argue that annual budget deficits are irrelevant because the GDP to debt ratio remains strong while simultaneously arguing that we would be in a better position if we hadn't lost the revenue from the GST cuts.
the disconnect is yours! Think debt versus economic output and what the degree of that output means in terms of debt... gee, what's it called again?
And ya, completely unrelated, that lost GST revenue could have many targets - even applied to debt... or COVID-19 mitigation/recovery. Try again; try harder!