The main difficulty here is comparing Klaus and Hans heights at simultaneous times. Note that the elements of xh and xk are not at simultaneous times. So if we start a stop watch when Klaus jumps, then the time on the stop watch corresponding to the first element of xk is zero, but the first element of xh is 5. So we can't just take the two vectors of heights xh and xk and look element by element to see when they are very close (intersect) as they are not aligned in time.
One way to deal with this would be to rewrite your equations of motion to just use one common time, e.g. a stop watch that starts when Klaus jumps.
Another approach would be to use your data to interpolate values for Hans position at each value of Klaus time, so something like
xhInterp = interp1(thans,xh,tklaus);
delta = xk -xhInterp;
ylabel('interception distance [m]')
[deltamin,imin] = min(abs(delta))