In verse 13 John does not see the elders. He merely says 'one of the elders said to me'. This is the same thing when he said: 'And I heard the number of those who were sealed, a hundred and forty-four thousand.."
You are not understanding my line of reasoning, so I will explain it to you in the simplest terms I know how.
Revelation 7 is talking about the earth. It cannot be talking about heaven because the vision never switches gears into heaven. The setting never changes. The central theme of the earth never changes. It is often used as proof that this vision is about heaven because it mentions the 144,000 but John merely says 'he heard' the sealing, not that he saw the sealing. That is my point.