So my conclusion is without drilling a small hole through plastic on the inner shaft there is no practical way to re-anchor the two shafts together.
If you just put adhesive or melt plastic into the hole the contact would only be flat surface to flat surface. Very little effort would be needed to shear that chemically bonded joint. Now if you drilled a hole into the plastic and filled it with adhesive or plastics the joint would have an actual shear joint.