Is there a better solution than the U-shaped tailplane for this Airbus concept?
In airplane empennage design, there is a thing called Tail Volume Coefficient. Mind you, there are no volumes here, but you are working with $m^3/m^3$. It is calculated as follows:
Horizontal tail volume:
$V_{HT} = \cfrac{ l_{HT} \cdot S_{HT} }{ c_{REF} \cdot S_{REF} }$
Vertical tail volume:
$V_{VT} = \cfrac{ l_{VT} \cdot S_{VT} }{ b_{REF} \cdot S_{REF} }$
here

$c_{REF}$ - mean geometric chord (~MAC)
$b_{REF}$ - wingspan
$S_{REF}$ - reference wing area
$l_{HT}$ - horizontal tail arm
$l_{VT}$ - vertical tail arm
$S_{HT}$ - horizontal tail area
$S_{VT}$ - vertical tail area

Now, with that in mind, you can have a perfectly reasonable cruciform solution, U-tail, H-tail, or triple-tail solution, or whichever.
However, freely choosing empennage configuration is not the only condition in design. Engineers likely have other requirements. These two vertical stabilizers (VS) look relatively slender. Perhaps a single VS would be too slender and cause structural issues, perhaps flight dynamics department required better yaw or sideslip control, in which two VSs would maybe be proved better. I think Russians designed An-225 with an H-tail to carry extreme payloads (like Buran), whereas Americans didn't modify 747's empennage for Space Shuttle carrying. There are a number of considerations here. One of which, mind you, is also aesthetics, especially for a passenger airliner.
So, is there a better solution than the U-shaped tailplane for this Airbus concept? It depends. There is no single universally best solution in these things.

Equations from S. Gudmundsson: General Aviation Aircraft Design