Very interesting test indeed.
Although the epoxy is the strongest I still would not trust it without glass.
Epoxy glass structure is way stronger than wood. Had she been using even a single thin layer
of glass epoxy to strengthen the joint, she would not have been able to break it.
The wood would have broken before the joint broke.
The effect of epoxy vs. glass epoxy can easily be tested with two identical pieces of plywood or wood strips.
Paint one piece with epoxy on both sides, and laminate the other piece with epoxy glass on both sides, then try to break them.
The results will be obvious.
And also, when epoxy gets a crack, the crack continues easily along the seam, and the seam immediately breaks.
If the seam is laminated with glass then not only it will prevent a crack from "traveling" but it will prevent a crack from being
created at all.

JP