I'm iffy about that. If you copy/dump text out of a terminal, what characters do you get for the doublestruck cells?

Plus, just complexity wise, I'd much rather just have a DCS sequence to draw vector lines like the article's suggestion than first send all the borders then home the cursor, send the overstrike sequence, send all the content, send the overwrite sequence. That has so many more places where a session gets trashed by accidentally sending the wrong control character.