You are correct in saying you COULD be taxed twice on gains, however it depends whether you are in pension mode or accumulation mode.
If you are in pension mode with a pension account balance of > $3M, I see nothing that says you will have to pay tax twice as you pay no tax on realised gains in pension mode. The new tax will capture realised and unrealised gain at a rate up to 15% on the proportion of funds over $3M.
If you are talking about a realised gain in an accumulation account with a balance of >$3M, then you will pay the usual 10 or 15% on the realised gain and then up to 15% on the increased overall balance, so yes you pay twice.
The Carlos example does in fact make sense. Nowhere does it say his whole $10M is in his pension account. 5% of $3M is $150,000.
