andraz has it. It's not a slippery slope. ATC has always had the right to call for an abort. The circumstances that would require that have already been well discussed, and pertain to an ATC awareness of a dangerous situation that has developed/is developing since the aircraft commenced to roll.
Missing bags, notified by the operator, are not going to meet that criterion.
It is totally the pilots decision as to whether to stop or not, once the stop call has been made by ATC. Below 80 kt or thereabouts, I'd expect the pilot to stop. Above that speed, maybe, maybe not, depending on the nature of the dangerous situation, and how lucidly it was communicated and understood. Above V1 (which in the tower, we have no way of knowing, but I'd guess is typically about 2/3 runway remaining) definitely not.