'I'm not God' means we submit to God's declared standard, not that we withhold judgment

He agrees that it's not up to humans to decide what is sinful — that authority belongs to God alone. But he argues the conclusion goes the opposite direction: because you're not God, you have no authority to override what God has declared. He uses the analogy of a store employee citing company policy — not my call, it's the policy. That is a humble position. He then goes to Isaiah 5:20 ('woe to those who call evil good and good evil') to show that declaring homosexuality acceptable is the actual act of playing God — reversing his declared moral order.