To me, running a long gun isn't the same as public concealed carry. Thumb safety can and should be massively trained into the owner if that's the choice he makes. But I've seen the video of jewelry store guy not get a shot off due to the safety.
I honestly don't put 1/20th the pistol practice in that I should. No damned way do I practice enough to run a thumb safety gun. I get that it can be fine for others though.