When I attempt to change either .row to .col or .col to .row in the complete code from here, I get a PTX error, basically saying that is an illegal choice or an illegal instruction.
ptxas /tmp/tmpxft_00040ec9_00000000-6_t153.ptx, line 105; error : Illegal alayout '.col' for instruction 'mma'`
So the question seems moot to me.