I think this attack only works if you argue his senility allows him to be taken advantage of by other, nefarious actors.
Tell voters that the reason they aren't able to make a call to the Social Security Administration or visit a National Park is because Elon was able to dupe the senile old man into allowing them to gut those administrations to pay for his tax cuts.
Uh, Musk? Lol, the attack writes itself.
Yes - read the next sentence after the part you bolded. 
My bad. I like your instincts, I think that line of attack is a lot more effective than whatever...it is that Democrats are doing now. As for Dems running in red/purple states, I'd just campaign against Musk and McConnell and leave Trump out of my mouth.
I mostly agree - Trump is good for rallying the D base but obviously campaigning against Trump alone is not enough for low propensity or swing voters. Attacking Trump directly obviously is not persuasive to a lot of people. It's unclear how much of this Elon will inherit - most Republicans seem to like him and the conservative media world seems to be putting in the work to align him with Trump and work with the base. But I still think he's vulnerable to attacks in a lot of ways that Trump is not.
Attacking Musk is a good (not perfect) test of the "Trump has something no other politician/political figure has" hypothesis. Obviously he isn't a politician but in a lot of other ways he has to be the most Trump-like figure in politics - wealthy and famous (quasi-) celebrity with dubious prior politics who inserted himself into politics in a novel way, mostly as a force of destruction. If Dems are smart they'll know how to differentiate him from Trump. But of course, there are many reasons to suspect they will not do it or will not do it effectively.
