I must admit that over the board it did not occur to me to double here. I asked John O'Hagan if he would have found this cube over the board, and here was his response:
"I would've cubed. 7 PoH's & fan is a big mkt loser, likewise hit loose and fan, plus the non-hitting D6 is mostly a mkt loser as well. The race is close,gammons heavily favor your side since you have an advanced anchor, and you might be able to hit his blot on the 23 pt. if you hit loose and he hits back, so it sure looks like a cube to me."