How would you handle this?

[Del-Blue]

As the PU on this play, I would have seen the BU with the OBS, but as the runner rounds third and I see the ball comming back to the infield, I am now getting ready for a play at home. I don't have the time or the inclination to recheck with the BU to see if s/he has lowered the arm, so therefore I will make the call at home, than look to the BU to see if the OBS was upheld to home. It is now up to him/her to finish the play.