Yes, that is exactly what he is saying. Yes, it is completely absurd and would undermine the bedrock principles of our legal system. However, apparently somewhere between 3 and 6 members of the US Supreme Court may be seriously considering it.
(To be fair, he does claim that this absolute immunity would go away if half of the House and 2/3 of the Senate decided to impeach the President.)
This article starts off as a response to another article, but doesn't link to the article it is talking about! I found that frustrating and poor form, community-wise.