I just want to spread this because people often confuse single-payer and Medicare for all:
Medicare For All was always an ambiguous term run by Democrats to include both single-payer and public option. Adam Green of the PCCC has stated that campaigning on Medicare For All with the inclusion of buy-in plans would be a good thing, so attacking someone for the use of a term that was supposed to be ambiguous, and has previously included public options too, seems odd.
Sure you can complain he doesn’t support single-payer, (By the way the popularity between “Medicare For All” and “eliminating private insurance” are quite different supporting the claim that M4A is an ambiguous term), but he is not claiming to and it’s just a difference in implementation path. Here’s a Vox article talking a bit about the “Medicare For All” term https://www.vox.com/policy-and-politics/2018/7/2/17468448/medicare-for-all-single-payer-health-care-2018-elections
This is why “Medicare for All” and “eliminating private health insurance” polls so differently.