There's like 20 things he could do all the way from a public appearance down to simply releasing medical records. He's doing none of them.

When evaluating such things, I look at motivation. I put myself in the other person's shoes, and ask what set of circumstances or motivations would cause me to act as I am?

Take for example the lot of people who make outlandish claims about hover propulsion, free energy from drinking water, etc.
I put myself in those shoes, and I say 'okay, I just built a device that turns water into power. What do I do?'
Most likely I patent the thing, build 50 of them, and send them off to research labs for evaluation. When everyone concludes my thing works, I start licensing the patents for $billions and I retire.

On the other hand, let's say I invent a water-to-power machine but it doesn't work. What do I do? I act sketchy, try to appeal to people without much sense, try to get their money.

Which one more matches the behavior of the person advertising the free energy machine? The second one? Then I guess it's probably bullshit.

Same deal here. If I was McConnell or his staff and I was alive and was going to return to the Senate, I'd post a video, I'd release medical records, I'd do something to reassure my constituents that I will continue to represent them.
On the other hand if I was a political director for a dead or brain-dead or almost-dead Senator, and I didn't want the opposing Governor to appoint a successor, I'd do whatever it took to delay the world realizing that the Senator won't be returning ever. Delay, Deny, Defend. Then once the deadline passes, we announce the Senator has 'made an unfortunate turn for the worse' and no longer is able to return. And our defense against fraud is someone we pay off to swear that when our brain-dead comatose Senator was asked if he'd return, his eyelids twitched twice for yes.

I thought the best way to get out of a bad position is to avoid getting into one in the first place?