The quick fix would be to use the appropriate size bolt and nut in place of the pin. That will hold the outer flange relative to the inner flange.
But I agree, the flanges should have been made heavy enough to take the pressure. Notify the manufacturer, see what they have to say.
I've considered this, and bolts/nuts wouldn't be too annoying given that I usually keep the snowblower on all winter unless I start doing tree work. However, wouldn't be bolt/threads get destroyed by the movement of the blower?