

In this case, your assessment is fair - user is harsh, name-calls, and does talk down to the person they were responding to/the reader. I got lost in the chain.
Regardless, accusations of purity testing come up more than enough online for my liking and it isn’t always in response to righteous condescension, as you aptly described the user’s behavior in this example.
The onus is on potential progressive or leftist presidential candidates to show up - it’s their decision. It takes a tremendous amount of courage and boldness to enter public consciousness and face scrutiny in every direction.