In other words, if you were in uniform, would you follow orders and fight for President Harris?
Johnson may be the best of the (limited) options we have right now.
How would that work?
Better a sentient idiot than a zombie in that case, so shedding Joe would be a step in the right direction. Johnson may be suboptimal, how well he performs under such fire isn’t well known to us, but I don’t think he’s an idiot. So I’d agree with your conclusion. Moreover he represents a district in which I suspect the largest part of the economy is an Army base. So he must at least fake well having good relations with the military to get elected. If there’s anyone competent left to command at the Pentagon he’s probably workable.