You answered your own question. Democrats are afraid of the guy. He shook their ivory towers and they fear he may finish the job.
Further, I don't think he can win in 2024.
I don't think he would get the nomination. Unless of course your party turns him into a martyr. The old saying, "let sleeping dogs lie" comes to mind.
Let the Commander in Tweet go away. His followers will eventually dissolve. Guess what, they were among us before he took over. The "proud boys", the "clan", BLM, they have been here for decades under other names.