Yes.

But here they are deciding between "pushdown o.status==shipped" and "pushdown u.email==address@", in parallel both, then join (which they already did) or first doing "u.email==address@" then pushing down "u.id==o.user_id" mostly.

This is a judgment call. Their planner is pretty dumb to not know which one is better, but “push down as much as possible” doesn't cut it: you need to actually decide what to push down and why.