unless there's a way to reduce the thrust, such as blowing off the nozzle. Consider the worst case scenario where most of the solid propellant has been burnt, resulting in high acceleration due to the thrust to weight ratio*. If the stack is accelerating at a high rate, say 4Gs, then the launch escape system will have to be powerful enough to pull the CEV away from the stack with an even greater acceleration, both upwards and to the side to get clear of the exhaust plume**. This is by no means impossible but it does mean the LES has to be very powerful and heavy. On a liquid fueled booster, you can rapidly reduce thrust but that's harder to do with a solid.

*By careful design, you can control the maximum acceleration during the solid burn by adapting the propellant geometry to reduce thrust near the end of the burn. This would be different from the Shuttle's SRB design but it could use the case casing.

**The Apollo LES had deployable canards to create aerodynamic sideloads, perhaps helping the capsule get clear laterally from the booster stack but primarily to rotate the CM to a heat shield forward attitude for parachute deployment. They'll probably do something similar with the CEV LES. As a data point, the Apollo LES weighed 8,500 pounds. It's likely that the CEV LES will be considerably larger.