Gopher Plant AKA SilverSpurge AKA Euphorbia Rigida

The plant had mystified me when I first spotted it in May 2019. Since then, I'd taken a few videos and stills of it, and a couple from a different site. Earlier this year, I stumbled across a YouTube video that included a snippet and ID (Euphorbia rigida) of the suspect plant. Read the entire article and comment there, please.