A flat geodesic with a periodic asymptote

We construct a closed surface of genus $2$ with nonpositive Gaussian curvature and a complete nonperiodic flat geodesic asymptotic to a flat closed geodesic. The metric is of class $C^{3,1\mathrm{/}3}$ and its curvature is of class $C^{1,1\mathrm{/}3}$, but not $C^2$. Thus the periodic-asymptote obstruction for smooth surfaces does not extend to $C^1$ Gaussian curvature.