Inadvertent Whistle - what's the POI?

[rfp]

Team A has the ball out of bounds on their front-court baseline. Inbounder A1 holds the ball through the plane where defender B1 legally swipes it out of his hands since it is on the inbounds side of the plane. Partner blows whistle thinking it's a technical foul then comes up to me for help, realizing it was a legal play. We decided to go with the AP arrow, but upon further thinking, I believe we should have returned the ball to Team A for a throw-in since Team A was last in control at the time of the inadvertent whistle. Game ended up a blow-out, so no impact to the call either way. What's the POI in this sitch?