I'm guessing they contain some combination of pattern/regexp type stuff, and interpreted code/scripting with trigger criteria, etc. that all gets loaded into the "engine" that actually runs the threat detection.
On the scale of "no one bothered to put error handling or validation in" to "a subtle problem exists for this given input"; you and I lack the information to make a judgement.
Think about this a little harder: what do you know about the number of customers affected? We do actually have enough information to make a judgement - bricking millions of critical systems, a very high percentage of their total Windows customer population, tells us that they don’t have progressive rollouts, don’t fail into a safe mode, and that if they do have tests those tests are catastrophically unlike anything their customers run – all they had to do was launch an EC2 instance and see if it kept running.
But no, saying "channel files aren't kernel code" is just hilarious, considering the channel files define how the actual kernel code is supposed to behave, so it might as well be kernel code. Especially when the bad behavior in question is triggered by bad channel files!!
