my 2013 1190r had the "flashing brake light on hard acceleration" issue as well. When doing a trip through eastern Europe last year all group members reported that the brake lights of both KTM 1190 (brand new T and my R with 10000km) were perfect indicators for road condition. Every mayor bump or hole in the road makes the brake light flush. During the 8000km tour the problem got better due to bikes getting more and more dirty. Sounds to me like the weight of the rear brake lever is already sufficient to trigger the brake light during hard acceleration or bad road surface.
In addition the brake light is programmed to start flashing under extreme braking - but that might be unique to Europe as some newer cars do the same...
The Problem with the brake light is known to KTM (my dealer is very very close to factory) and supposed to be fixed in future SW update.