I don't think the throw was online, and would've pulled the catcher off the plate. I suppose you're right because then he wouldn't have tried the sweep tag where he lost the ball, but Arozarena only would've been out because he had fallen, which neither the C or 1B knew. So I think the Muncy made the right baseball move, even if it didn't work out.
I think the C should've had a little better peripheral vision to know Arozarena wasn't bearing down on him, or the P should've yelled it to him. Lots of crowd noise though.