No, not really. Single issue voters are fairly unusual in the dem party. There are always some, no question, but the very small size of the peace protests compared to those during, say, the Vietnam War era demonstrates a fairly niche issue imo. While most dems believe in peace for Palestine, relatively few would rank it among their top issues.
Regarding Biden's diminishment, delegation is the most important skill a leader can possess. It is not a leaders responsibility to make all the decisions, but to organize and provide vision for a group of people that can accomplish far more than any individual. Many people past their youth understand this, due to direct life experience in the broader world. Biden's diminishment would have had minimal impact on his actual presidency. At the polls, however, yes it definitely was a concern, eventually leading to him dropping out after all. The idea he actually could not win was very, very overblown though. He was still in the running. I think the broader concern was his impact on down-ballot races.
Regarding uncommitted actually being on some ballots, it seems you're right. Thank you for the correction, that's actually sort of funny. lol