I don't think it was as big as an issue as it sounds here. Caucus doors closed at 7. No one is allowed in after that time. It probably would have been better to wait, but we were in such an unusual territory where Trump was so far ahead in the early votes.
To further clarify for people that are unaware, AP, Fox, etc have statistical teams that have preset rules for race calling. They vary somewhat on what they do, but it is all very objective- it got Republicans big mad last election when Fox's team called Arizona for Biden. As we saw in the Fox defamation case, not even the Fox executives can really interfere with these teams. They are just following the math.
These calls can sometimes get it wrong, but that's just the risk. They don't wait for 100% certainty, but fairly close to that.