This is very dangerous, the plastic retaining loop is not load bearing and it can be absent or broken, even if it holds your weight you can cause an uncontrollable fall in your second by simply tripping and tension on this carbiner can prevent the autoblocking function from operating at all
Consider also that auto-blocking devices are usually most critical in situations where the belayer is injured, possibly unconscious or deceased. For example due to rock-fall or a medical incident.
Specifically, during a lowering activity it is OK and sometimes recommended or necessary to leverage your body weight.
As @Manziel shows the proper way to rig the lowering system of a direct-belay device using the carabiner to redirect the force , in certain situations, it may be very hard to release the device by pulling on release sling without major leverage, in which case you can consider clipping the lowering loop to your harness to provide body leverage.
You can certainly do a redirected belay, imagine very uneven top-rope
In some situations, a direct belay may be used.
But your combined solution is a death trap since the guide is hard clipped to the anchor through the forged loop, an overconstrained system.