he went with the party when, traumatized in the nineties, it shrank toward the imagined center
Did he? Or did the party move toward him in its trauma? I'd say the latter, if "the imagined center" is understood to mean "the monied class."
If you take a look at his top donors, I think you might change your view that he is no longer "particularly in thrall to the banking [investment] industry."
Your rabid mustang analogy I agree with completely. Since I'm uncertain rabies leads to dementia and/or incredible stupidity, I might add an adjective or two to describe a man who would have the temerity to cut funding to the WHO in the midst of a global pandemic. By extension, two years hence when hopefully we have a vaccine with which to fight this killer, if the American People cannot learn the absolute inanity of having our health insurance tied to our employers from this experience then they are no better than he. How the phrase "We need a National Health System" is not running across the lips of every American is beyond me. And as far as Joe "moving left with the party" goes, I'm not exactly inspired by the conjecture that he's willing to move the Medicare eligibility age down to 60. That's not a trot in the right direction, that's merely turning the head in the right direction with no further movement.