Yes. Well...
IIRC -- and there's no guarantee of that! -- Dr. Hoffman pooh-poohed any such suggestion of a presently warm and anciently hot Martian subsurface, mostly because his temperature profiles showed that Mars must have become a cooled off cinder way early in its history. If so, then of course he would believe that CO2 would be the primary volatile on the Martian surface.
In fact he was certain of it.
Now these girls come along and pooh-pooh the plausibility of his hyporthesis.
As if they knew anything.
;-)
Cheers, BRFelix