Second main...no, wait!
This situation was relayed to me from an SCG Event and I wanted to hear how other people would rule this. Situation: Anson is playing Eldrazi Tron, while Noah is on Death and Taxes. During Anson's precombat main phase, he casts Thought-Knot Seer. With the ability on the stack, Noah casts Path to Exile targeting Thought-Knot Seer, then activates Ghost Quarter targeting Anson's Urza's Tower. Anson floats three mana in response (Tron is active) and fetches a Wastes. Path to Exile resolves and Anson gets another Wastes, Thought-Knot Seer's abilities resolve and Noah draws a card, then has a card taken by Anson. Anson then taps Eldrazi temple for two mana and moves a card from his hand towards the battlefield, saying “Okay, second main, no, wait, cast Reality Smasher” (no pauses). At this point, Noah calls a judge and claims that because Anson said second main, they're in that phase and Anson doesn't have the mana to cast Reality Smasher anymore.
I feel like this one could go either way, and I believe it was ruled that they were in precombat main. I probably would have ruled it to be in postcombat main, but then again, I didn't have the luxury of seeing the interaction for myself, only hearing about it afterwards. Assuming everything above is how things happened, how would you rule in that situation?