AP arrow
 

Situation…2nd quarter ready to begin…2nd horn sounds…team to throw the ball in still in huddle…place ball on floor and begin the count…5 second violation called…opposing team gets the inbounds…off we go…Question: Do we change the direction arrow for alternate possession?

Yes. Arrow changes when inbounding team violates.

Agreed.

Does this fall under the new rule that a throw-in must be legally touched to end? And that the ensuing throw-in is rewarded for the violation? This is a good question by the OP.

No, this has always been the rule. The throwin also ends when the throwin team violates.

6-4-5 . . . The opportunity to make an alternating-possession throw-in is lost if the throw-in team violates.

And for 26 YG:
6-4-4 . . . The direction of the possession arrow is reversed immediately after an alternating-possession throw-in ends. An alternating-possession throw-in ends when the throw-in ends or when the throw-in team violates.