The NHRA rule book is rather difficult to figure out on many points. That chart is also shown on the last page of the rule book. It also states "In no way is this Quick Reference Chart intended to supercede or replace the current NHRA rulebook."
A new rule was implemented last year that required certain ET class cars 10.99 and faster to have roll cages. These "certain" cars would fall into that catagory if the factory firewall was modified [A/C removal is NOT a firewall mod]. Stock and super stock classes have specific classifications where a cage is required. ANY car faster than 10.0 or 135 mph must have a cage. SOME others also must have a cage at 11.0 or faster, but not all cars.
I verified this with local NHRA tech inspectors and this is their interpetation as well. I know many NHRA stock/superstock participants, and this is how they are set up and race in Divisional and National events.
Local or Divisional tracks and officials may have different opinion?