I do exactly the same thing, using a tap of the regen paddle to cancel out of ACC. For me, it is less of a trust issue, and more that I like the way I slow and stop more than the way ACC does it.
I just tried it with Siri. She said: "Apparently we intelligent agents will never live that down.." Tried again. She said: "Without your space helmet, Tom, you're going to find this rather...breathtaking." Tried again. She said: "I'm afraid, Tom, I can't do that. Are you happy now?" Fourth time, she repeated #3. I told her, "Yes." She turned off.