I don't know if I can accept your premise about Trump's behavior being caused by mental decline rather than desperation. As an example, he was impeached last year for his actions around the Hunter/Joe Biden faux scandal so that's no new. He has been critical of Fauci since the beginning when he wouldn't toe the party line and garnered higher credibility ratings. He tried to appeal to suburban women in '16 (build the wall) and '18 (caravan) so that's not new. He has been talking about low-flow toilets at least a year now and he calls for everyone he doesn't like to be jailed at some point.
To be clear, I certainly believe Trump is mentally unstable. I also believe that the doctors are pumping him full of steroids and other "uppers" which is why he is more energetic now than he was a few months ago when he leaned on the podium throughout his speeches and couldn't lift a drinking glass. Now he is dancing in the streets.
However, to make his behavior be about losing his grasp on reality absolves him of his culpability, much like the way a senior with dementia may say cruel or crazy things they don't mean or even realize they have said.
Trump knows what he is doing; he knows what red meat to throw at his supporters. https://medium.com/illumination-curated/in-a-religion-your-savior-dies-for-you-in-a-cult-you-die-for-your-savior-7a3deb640986
I wrote about the Cult of Trump. Trump and his supporters are coming closer to the Kool-Aid drinking moment and so yes, it does feel more frenetic and erratic. But Trump is still in charge - of himself and his followers, to be sure.