Projectors have limitations to begin with. And this idea takes all of those limitations, and adds even more inefficiency to them.
A major hurdle in projection that still remains today is brightness.
A projection screen that offers 50% optical transparency throws away at least 50% of the light energy that hits it: Of all the light being directed towards that screen to produce an image, no more than half of it can be reflected.
And furthermore, a screen with 50% transparency doesn't look very transparent at all. A hypothetical frosted screen that is suitable for projection with 50% reflection and 50% transmission might not look even a tiny bit like a window.
In short-term visual effects for stagecraft and amusements, that's not a big deal. "Oh, we lose fifty or sixty or ninety percent of the light we project for this effect? No worries; we'll just use a bigger, brighter projector until the effect works. Call Andy over at the rental house and see what he can get for us."
But in long-term use, that kind of built-in inefficiency is mostly a non-starter: It's inefficient to over-build the equipment in this way, and it's inefficient to burn (waste) the energy to keep it going.
Maybe with some massive improvements in material science we can have a semi-transparent screen that concurrently reflects and transmits light over-unity, but we're not there yet. But to hazard a guess, it's probably easier to accelerate a mass beyond the speed of light than to pull off that particular trick.
(Meanwhile, see-through/transparent LED-based displays with decent-ish optical transmission? Whether good or bad, that technology seems to be right around the corner.)
It's not that bad actually, energy wise. The 4k TV power consumption is about half of this projector. Any typical projectors using bulbs are more power hungry.
So TV < laser < bulb. The short throw design doesn't seem to change the numbers much.
