It may not be definitive evidence, but what little information has been made available certainly supports Stebo's conclusion. Firstly, I highly doubt Trump would have received oxygen supplementation, let alone Regeneron, if he wasn't doing at least somewhat poorly. Secondly, we have four years of Trump's presidency to suggest that were he doing fabulous right now, the tone of his videos/tweets/the WH in general would be a LOT different. You know as well as I do that if Trump were doing really well, he'd be the first one to let the world know. And sure, everyone is saying that he's doing decent; but they aren't really selling it, for the above reasons.