  We investigate the mesoscopic transport through a twisted bilayer graphene
(TBG) consisting of a clean graphene nanoribbon on the bottom and a disordered
graphene disc on the top. We show that, with strong top-layer disorder the
transmission through such a device shows a sequence of resonant peaks with
respect to the rotation angle $\theta$, where at the resonance angles
$\theta_c$ the disc region contains one giant hexagonal moir{\'e} supercell. A
further investigation shows that the value of $\theta_c$ shows negligible
dependence on the disorder strength, the Fermi energy, and the shape
distortion, indicating the resonance is a robust geometric feature of the
moir{\'e} supercell. We explain this geometric resonance based on the bound
states formed inside the moir{\'e} supercell, with their averaged local density
of states dominating at the AA stacking region while minimizing at the AB
stacking region. By increasing the interlayer distance, the peak becomes less
pronounced which further confirms the role of interlayer coupling. The results
presented here suggest a new mechanism to tune the quantum transport signal
through the twist angle in disordered moir{\'e} systems.
