Def not a gimme. Also he prob can't see the runner going to first. But I do think the unquestionably correct play is to first, esp. with your catcher pointing and not ready to catch. My point is really that these guys usually are so good when they make a mistake like this it's shocking.
Having just seen 10/11-year-olds play baseball this evening, we take for granted the decision making major leaguers display 99.9% of the time. Dude had a tiny mental lapse and did exactly what my kid would have done.