Right on the spot. When in doubt = no go.
But i still say she's (The article lady) not right in calling it a "no pen". Fifa clearly states that in those kind of situations it's up to the referee's interpretation as you even said, we've seen similar situations where the referee says yes, it's a pen. In this case it was a no. Was he right or wrong? Neither, he did what he thought was best following the rules set by FIFA.
Now if he did that on purpose i don't know.
(IMO The Vucinic ones were both 100% clear, the one in our favor and the one against us.)