Republicans werent promoting Sanders because theyre afraid of Biden. Theyve been promoting Sanders because the Trump campaign will be making a strong push for his supporters in November.
The only thing Biden will have going for him during his run against Trump will be the sympathy vote. It wont be a pretty sight watching Trump take Biden apart during the debates. Who doesnt have a loved one theyve lost to age related dementia? Trump will have to show compassion when warranted.