That's true, But even if I take the rule of thumb where the rearward 25% to 30% of the wing area is used as the stabilizer then it's still only up around 19 to 20 oz/sq foot.

In truth though it's not so much about effective wing area as it is that airfoils that are self stabilizing tend to have a lower maximum lift coefficient. But it comes down to the same thing at lower speeds.

But by any standard be it the full wing, the front 2/3's as the "effective" wing area or a lowered max lift coefficient. He's still got a very light wing loading for this size of model. It isn't going to have any big issues with slowing down even in "normal" flying mode. And from there he can play with the nose high vortex lift mode that high sweep angle delta wings are so good at.