Two thoughts on radial lacing the non-drive side.....

When doing so you decrease by half the number of drive spokes. On 32 spoke wheel there are 16 drive spokes so your pedaling forces are divided amongst 16 spokes. With a radial laced non-drive side you only have 8 spokes handling the load.

If I remeber correctly shorter radial spokes (in comparison to 3X or 4X) have a higher tension with same dish. This increase in tension will, obviously, increase tension on the hub. The higher tension, will, as S notes, decrease slacking of the spoke which may lead to less breakage at the elbow.

My personal thoughts after 2,000 plus wheel builds:

If your non-drive side spokes are going slack under pedal forces your wheel is not correctly tensioned/built from the start. Fix the problem of flexing first.