A gas fired cook top is allowed to be fed from any general purpose circuit, it is also allowed to be fed from the SABC as the exception #2 to 210.52(B)(2) remember it is an exception to be on the SABC not a requirement.
It might be easier to just pull a receptacle down from a counter receptacle if there is one located close to the cook top, also look to see if there is a receptacle on the other side of the wall or even a switch that might have a hot and neutral as both would be compliant to feed it from as per the NEC.
pig tailing to go from the #8al to #14 or #12 at both the old receptacle and breaker could be done but might be more costly with the special connection requirements then if there is another circuit is close by to feed from, but you have options just choose which one will keep the cost down and make your job easier for you.
I agree with post 3 (sorry little bill) as the 2011 did add the exception to not require TR receptacles in some areas where children would not likely have access to it, the 2008 addition of TR receptacles without any exception never made any sense and I was glad they were added in 2011 even though we voted them out of the Indiana codes (except child caring places 406.14) 406.12 was removed here.