Hector said:
-When Freeza said his power was 530k, he was referring to his full power in that form. Why was he supposed to mean something different when he talked about his 2nd form?
That's ignoring the differences in context between them. Freeza specifically referred to his power at the moment when talking about his 2nd form's initial power:
Chapter: 296 (DBZ 102), P8.2-5
Context: after Freeza reaches his second form
Vegeta: “I'm-impossible…How can this be?...”
Gohan: “W-we’ll be killed…”
Kuririn: “Th-this is a nightmare…”
Freeza: “Heh..heheh…Watch out…
Now that I’ve turned into this, I won’t be as gentle as before…”
Chapter: 296 (DBZ 102), P9.1-2
Freeza: "At any rate, my power is excessive. Perhaps I've overdone it... Kukkukku... Incidentally,
if [my strength] were put into battle power, it would be over 1,000,000, surely..."
Vegeta: “Wh-what!?”
These statements wouldn't make sense if not referring to his current power if he needed to power up further to reach this standard and when the whole context of it is referring to the current situation for the group. By comparison, Freeza's 530k statement is explicitly to hammer in the gap between him and Nail and what he won't use.
Chapter: 286 (DBZ 92), P5.4
Freeza: "My battle power is 530,000. But of course, I don't intend to fight you at full power, so you can relax..."
-Goku (max power pre zenkai: 900.000, didn't expect to get another zenkai, never considered 20x kaioken before fighting 4th form Freeza) stated he might not be able to win only when Freeza transformed again. That would make no sense if 2nd form Freeza was already way above 1 mil.
He said that about 3rd form Freeza, so this point is redundant by default.