The fact that the 0-24 age range (typically dominated by car accidents and suicides) doesn't see much change suggests that the effect you are suggesting is small or nonexistent.
Your argument doesn't prove that. Using that logic, given that we (collectively) make much fewer car miles due to the lockdowns, we should see a downward change in that age range. Since we don't see a change, that may mean that suicides are on the rise, offsetting the reduction in traffic fatalities.