The "possible shear layer from the NW" idea was speculative based on sat obs -- let's keep that in mind. The next descriptive update from TPC will be telling, because they have the advantage of Recon and other observation techniques, of course.

As to the countering idea ... systems in the formulative phases of development do not typically possess the power to alter their environment in that way. So I would be less inclined to concur with that idea. Stronger systems may be more resistant to weaker shear penetration into there cores; if there is shear in some intervening layer, it is not likely Karen has yet acquired the ability to prevent it from incurring.

I am also noticing that there is a lot of dry air situated over the western and northern Gulf. It is also possible that a lot of this disrupted convection is because mid level dry air had been ingested. Evidence to support that is a strong arcus cloud feature propagating to the N and NW away from the center this hour. Dry air mixing into the convection promotes cold down burst due to evaporation, and these outflow boundaries can be symptomatic of that taking place.