It's a good question, sir, these are my findings:
In the video, you can see that I (as D'vorah) cannot in fact block after the lighting ball hits me as I stumble into the trap, and I would only be able to do so if I was spaced out enough to where the full hitstun of lightning ball would end as I hit the trap. I too was initially confused by the term 'autoblock', but I believe it to mean the state where despite still being in hitstun, a player can hold block and still block a follow-up attack that hits even in hitstun. Reptile's Acid Spit also recieved this change, and the video accurately reflects what was shown on the initial NRS stream regarding 'autoblock'
You play Raiden more than me for sure, can you think of any scenarios where lightning ball would hit and then the player would need to immediately block in Thunder God? I couldn't find any because of the recovery of the projectile, but I would always like more data to go by. Thanks!