Out there, it does nothing for wing bending strength, so to call it a shear web is beyond misleading. The best I can come up with is that it keeps the tip plate and tip rib from leaning over if you were to pull too hard on the covering when installing, or, if the covering tension was unequal after all was said and done.
It may also be handy for installing tip weight, but it really isn't in the right place.
The kit comes with this "feature?" Just curious.....
Still, the plane looks good and like a capable flyer!
Dave